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8086：16位微处理器 ，16根数据线、20根地址线，可寻址1M字节； 8086CPU功能结构
总线接口部件BIU
执行部件EU
功能：负责与 M、I/O 端口传送数据、地址
功能：从指令流队列中取指令、分析指令
和执行指令
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8086CPU功能结构图
总
线
控
制
逻
辑
内部总线16位
总线接口部件BIU
执行部件EU
完成16或8位二进制数的算术运算和逻辑运算
通用寄存器组
包括数据寄存器和地址与变址寄存器。
生成20位物理地址
CS：存放代码段段基址
DS：存放数据段段基址
SS：存放附加段段基址
ES：存放堆栈段段基址
IP : 存放下一条要执行指令
的有效地址EA。
8086：6个字节
8088：4个字节
8086指令队列空2个字节（8088空1个字节），且EU部件没有要求BIU部件进入存取操作数等总线周期时，BIU部件就会自动从内存单元顺序取指令字节填满指令流队列。
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8086CPU内部有14个16位寄存器，可以分为以下三组。
8086/8088的内部寄存器
通用寄存器组
段寄存器组
控制寄存器组
数据寄存器
地址与变址寄存器
指令指针IP
标志寄存器FR
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AX
BX
CX
DX
目的变址指针
DI
源变址指针
SI
基址指针
BP
堆栈指针
SP
数据寄存器
DX
计数寄存器
CX
基址寄存器
BX
累加器
AX
数据寄存器
可分为两个8位，主要用于数据操作
地址指针寄存器
主要用于地址操作
8086的16位通用寄存器是：
AX BX CX DX
SI DI BP SP
8086的8位通用寄存器是：
AH BH CH DH
AL BL CL DL
对其中某8位的操作，并不影响另外对应8位的数据
BX:常用做存放存储器地址；
CX:作为循环和串操作等指令中的隐含计数器；
数据寄存器：
AX:使用频度最高，用于算术、逻辑运算以及与外设传送信息等； DX:常用来存放双字长数据的高16位，或存放外设端口地址;
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AX
BX
CX
DX
目的变址指针
DI
源变址指针
SI
基址指针
BP
堆栈指针
SP
数据寄存器
DX
计数寄存器
CX
基址寄存器
BX
累加器
AX
数据寄存器
可分为两个8位，主要用于数据操作
地址指针寄存器
主要用于地址操作
数据寄存器：
SP：指示栈顶的偏移地址，不能再用于其他目的，具有专用目的。 BP：数据在堆栈段中的基地址。
SP和BP寄存器与SS段寄存器联合使用来访问堆栈。
SI和DI：串操作类指令中，常用于存储器寻址时提供地址。
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通用寄存器的特殊用法(默认用法)
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段寄存器组
8086/8088CPU可直接寻址1MB内存空间。 存储空间采用分段技术，每段最大寻址64KB。
逻辑段可在整个1MB存储空间内浮动，但段的起始地址 低4位必须是0000B，这样在存放段地址时只存放高16 位，作为段基址。
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操作
取指令
存取数据
堆栈操作
目的串操作
访问：代码段
物理地址的构成：CS×10H+IP 访问：数据段
物理地址的构成：DS×10H+EA 物理地址的构成：SS×10H+SP 物理地址的构成：ES×10H+DI
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物理地址=段地址×10H+有效地址
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CS左移4位
20位物理地址形成过程演示
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表 8086的基本段约定和允许的超越段
8086的基本段约定和允许的段超越如表所示。 表中的“-”表示不允许修改。
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控制寄存器组
作用：存放将要执行的下一条指令在现行代码段中的偏移地址，它与CS相结合生成指向指令的物理地址。
特点：IP是一个专用寄存器，其内容由BIU部件自动修改，不能直接访问IP，但可以通过转移或调用指令改变其内容。
作用：存放指令执行结果特征位和对CPU运行特点的控制位。
特点：8086 CPU 中设置了16位标志寄存器，只用了9位，其余位用来扩展。9位标志分为6位状态标志和3位控制标志两类。
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AF：辅助进位标志
AF=1：数据的第3位（半个字节）需要向前产生进位/借位。
AF=0：数据的第3位（半个字节）不会向前产生进位/借位。
CF：进位/借位标志
CF=1：最高位需要向前产生进位/借位。
CF=0：最高位不会向前产生进位/借位。
PF：奇偶标志
PF=1: 结果的低8位中有偶数个1。
PF=0: 结果的低8位中有奇数个1。
影响全部状态标志:加法、减法运算。
影响部分状态标志:移位操作。
不影响任何状态标志:数据传送指令。
ZF：全零标志
ZF=1：运算结果为全0。不包括进位的情况
ZF=0：运算结果不为0。
标志寄存器
16位，只用了其中9位，唯一能按位操作的寄存器。
用于反映指令执行结果或控制指令执行形式。
6位状态标志：OF、SF、ZF、PF、CF、AF
作用：反映指令对数据作用之后，结果的状态，控制后续指令的执行。
3位控制标志：DF、IF、TF
作用：值不由数据运算结果决定，由指令直接赋值，决定后续指令执
行情况。
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OF：溢出标志(指补码)
OF=1：操作数超过了机器表示的范围,溢出。
OF=0：操作数未超过了机器能表示的范围,不溢出。
求解方法：最高位进位?次高位进位
字节允许范围：－128 — + 127
字允许范围：－32768 — + 32767
TF：跟踪(单步)标志位
TF=1，每执行一条指令后，自动产生一次内部中断，使CPU处于单步执行指令工作方式，便于进行程序调试，用户能检查程序。
TF=0, CPU正常工作。
标志寄存器
16位，只用了其中9位，唯一能按位操作的寄存器
用于反映指令执行结果或控制指令执行形式
IF：中断允许/禁止标志位
IF=1, 允许外部可屏蔽中断。CPU可以响应可屏蔽中断请求。
IF=0, 关闭中断。CPU禁止响应可屏蔽中断请求。
IF的状态对不可屏蔽中断和内部软中断没有影响。
SF：符号标志
SF=1：运算结果的最高位为1，如果为带符号数，则为负数。
SF=0：运算结果的最高位为0，如果为带符号数，则为正数。
带符号数的最高位为符号位；而无符号数的 最高位为数值位。
DF：方向控制标志位
用于串处理指令，控制从前往后、还是从后往前对字符串进行操作处理。
DF=1，每次串处理操作后使变址寄存器SI和DI的值递减，使串处理从高地址向低地址方向处理。
DF=0，每次串处理操作后使变址寄存器SI和DI的值递增，使串处理从低地址向高地址方向处理。
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存储器寻址
这时操作数在存储单元中，在指令中直接或间接地给出
存放操作数的地址，以存取操作数。这类情形最为复杂，我
们需要了解以下四个问题：
缺省的段寄存器
段超越问题
有效地址
不同的存储器寻址方式
我们常以 mem表示存储器寻址。
在指令中识别存储器寻址方式的常用方法就是看
有没有方括号 [ ] ，在其间的内容就是存储器地址的
一部分，往往是有效地址的全部。另外就是注意符号
定义过程，也经常用符号来表示对应的存储地址
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缺省的段寄存器
8086采用段，偏移的地址转换方式，即
物理地址 = 段始址 + 段内偏移
其中，段始址共20位，高16位保存在某个段寄存器中，低4位为0。在指令中出现的“地址”一般为偏移地址，而段始址可以通过缺省的段寄存器内容（×16）求得。缺省的段寄存器究竟是哪一个，取决于指令，寻址方式及涉及的寄存器。
用BX、SI、DI 间接寻址时，缺省的段寄存器为DS
用BP间接寻址时，缺省的段寄存器为SS，允许段超越。
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段超越问题
如前述，缺省的段寄存器取决于指令，寻址方式 和涉及的寄存器，但有时使用缺省的段寄存器并 不合适。多数情况下，允许程序自行选择段寄存 器，当然需要显式指定，这种情况叫做段超越。 段超越的基本格式为
〈段寄存器〉：VALUE
段超越位于需要段超越的指令之前，因此也叫段 超越前缀。VALUE指存储器地址
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例： MOV AL，ES：[2000H]
例： MOV SS：[3000H]，AH
例： MOV CS：[SI]，BH
有三种情况不允许段超越前缀：
串处理指令的目的串必须使用ES段
PUSH指令的目的和POP指令的源必须使用SS段 指令必须存放在CS段中
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有效地址
有效地址EA，就是段内偏移地址，是操作
数位置相对于段基址的距离，在8086中用
16位二进制数表示
问题：操作数均在存储器中，因此操作数（寻址） 就变成了找“存储单元地址”。
存储单元的物理地址计算
PA＝（段寄存器）左移4位＋EA
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位移量（Displacement）
此地址分量是指令中的一个带符号的常数（8/16 位），还可是符号名。
基址（Base Address）
此地址分量存放在寄存器 BX或 BP之中
变址（Index Address）
此地址分量可放于SI或DI之中。
由上述内容可看出，有效地址EA实际上是3个地址分 量不同的组合；如果存在两个或两个以上的分量，需要 进行加法运算，求出EA，但进行加法时要注意：是16 位的二进制无符号数。
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具体来讲，有以下几种组合情况：
EA= Mem
EA= (BX/BP)
EA= (BX/BP)+ DISP8
EA= (BX/BP)+ DISP16
EA= (SI/DI)
EA= (SI/DI)+ DISP8
EA= (SI/DI)+ DISP16
EA= (BX/BP)+ (SI/DI)
EA= (BX/BP)+ (SI/DI)+ DISP8
EA= (BX/BP)+ (SI/DI)+ DISP16
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不同的存储器寻址方式
可以分为三种：
不涉及寄存器： 直接寻址
涉及一个寄存器：寄存器间接寻址 和 寄存器相对寻址
涉及两个寄存器：基址变址寻址 和 基址变址相对寻址 可以参加存储器寻址的寄存器分别是BX、BP、SI 和 DI
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1.时钟周期 (T状态周期Clock Cycle)
微处理器内部操作的最基本时钟单元，宽度为时钟信号相邻两上升沿之间的时钟间隔。 时序概念
时钟周期由计算机的主频决定，是CPU的定时基准，例如，8086的主频为5MHz则1个时钟为200ns。
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2.机器周期(总线周期Bus Cycle)
微机处理器BIU与外部电路之间进行一次数据传送操作所占用的时间，包含若干个时钟周期。
3.指令周期(Instruction Cycle)
执行一条指令所需要的时间，由一至若干个机器周期组成。
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Intel 8086微处理器采用总线复用操作方式8086的16位数据总线和地址总线的低16位是共用的，典型的总线周期如图
基本机器周期
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等待周期TW：
如果在T3周期结束之前，存储器或外设未准备好数据传送，就要启动输入CPU的READY线使之变低电平，从而在T3和T4之间插入一个或多个TW等待周期，直到READY变高，转入T4周期，完成读写操作。
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图2-12 8086/8088复位时序
为了保证复位可靠，系统要求复位正脉冲信号宽度至少为4个时钟周期，加电启动要求宽度不少于50微秒。
复位时的总线信号和时序
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复位时的总线信号
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汇编语言的分段结构：
汇编语言源程序
数据段（DATA）
作用：存放程序运行所需要的数据和运行结果
堆栈段（STACK）
作用：执行数据的压栈和弹栈操作，以及程序中 的数据保护
代码段（CODE）
作用：存放所编写的程序的代码
用开始语句“SEGMENT”和结束语句“ENDS”来定义一个段
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语句类型
语句类型
指令语句
作用：产生相应的机器代码，指定CPU做什么操作。
伪指令语句
作用：不产生相应的机器代码，仅控制汇编过程。
宏指令语句
作用：由编程者按照一定的规则来定义的一种较“宏大”的指令，包括多条指令或伪指令 。
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CPU与存储器典型连接 设计地址译码电路
步骤：
（1）确定(扩展)地址线数
（2）确定地址分配
（3）画地址分配图和位图
（4）画出地址译码电路图并连接
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第二篇：高考英语第一轮复习 时态和语态复习.ppt.Convertor
动词时态
动词时态在历年的高考试题的考查热点，无论是在单项选择，还是短文改错中都占有一定的比例。书面表达的评分标准中对时态的运用也有明确规定。
I． 时态和语态的主要考点
1、考查在语境中判断动词时态的运用能力。常考的时态为：一般现在、一般过去、一般将来、现在进 行、过去进行、现在完成、过去完成、现在完成进行、过去将来等。 2、时间、条件、让步等状语从句中动词的时态；主从句时态呼应问题。
1 一般现在时的用法
1） 经常性或习惯性的动作
1
1. I ______ ping-pong quite well, but I haven’t had time to play since the new year.
A .will play B. have played C. played D. play
2.---_____my glasses ? ----Yes, I saw them on your bed a minute ago.
A. Do you see B. Had you seen C. would you see D. Have you seen
3.We will see to it that every child in the nation ____ good education ,especially those in the poor countryside.
A. get B. will get C. gets D .would get
2） 客观真理，客观存在，科学事实或表示格言或警句。
①Knowledge begins with practice.
② She said that the sea water is salty.
③In some parts of the world, such as in England , tea ____ with milk and sugar.
A. is serving B. serves C. is served D. served
④----The girl ____ weight recently.
----Yes , she _____ too much.
A．has gained ,is eating B. gains ,eats C. is gaining, ate D. is gaining ,eats
3）按火车、汽车、飞机等时刻表将要发生的事。此时句中有时有将来的时间状语，但不用将来时。此时主主语是物：车，船，飞机等
The train leaves at three this afternoon.
4）在时间、条件、方式、让步状语从句中，用一般现在时代替一般将来时。
①If it is fine tomorrow ,we will go to the countryside.
②----Put these glasses away before they _____.
----OK. I’ll put them in the cupboard.
A. have broken B. are breaking C. get broken D. will be broken
③I’ve brought my tennis things along in case we _____ time for a game tomorrow.
A. shall have B. have C. will have D. are going to have
④----Can I drive on the free way, Mr Green?
-----You can when you _____ a bit more skilled.
A. will get B. are getting C. will have got D. get
2 一般过去时的用法
1）表示过去发生的，和现在没有联系的动作或状态。
1.----Look! Someone has spilt （溢出）coffee on the carpet.（地毯）
----Well , it _____ me.
A. isn’t B. wasn’t C. hasn’t been D. hadn’t been
2.----I’ve bought a box of chocolates for our daughter. ---Oh, how good a dad! But she doesn’t like sweet things. _____ that?
A. Don’t you know B. Haven’t you known C. Didn’t you know D. Hadn’t you known
3.----Was Mary in the office when you arrived there?
------Yes , but she _____soon afterwards.
A. had left B. left C. would leave D. will leave
2）注意：一般过去时与过去进行时的区别：
一般过去时表示一个完成的动作，而过去进行时则表示一个没有完成且正在进行的动作。
I wrote a letter this morning. 今天上午我写了一封信。（信已写完）
I was writing a letter this morning. 今天上午我在写一封信。（正在写，不一定写完） 2
1.----Has Tommy finished his job yet?
----I have no idea of it ; he ____ it this morning.
A. was doing B. had been doing C. has done D. did
2.As she ____ the newspaper, Granny ______asleep.
A . read, was falling B. was reading ,fell C. was reading, was falling D. read ,fell
3.All morning as she waited for the medical report from the doctor, her nervousness_____.
A. has grown B. is growing C. grew D. had grown
4.---I’m sorry , I shouldn’t have been so rude to you.
-----You _____ your temper but that’s OK.
A. have lost B. had lost C. did lose D. were losing.
3. 一般将来时
1 .一般将来时表示计划、打算、企图做某事或来注定要发生的事情。
2 .表示将来时的四种形式
① will /shall +动词原形 ② be going to do
③ be about to do(正要干什么) ④ be to do
① be going to 有很强的计划性，打算干什么，而will表示谈话时临时决定的意图，具有临时性和偶然性。
1.----The telephone is ringing.
----I _____ answer it.
A. will B. am going to C. am to D. am about to
2. ---Alice, why didn’t you come yesterday?
---I _____, but I had an unexpected visitor.
A. had B. would C. was going to D. did
② be going to 可用来表达某种迹象要发生的事。而will 不能表示
Look at the clouds! It’s going to rain.
3. be to和be going to
①表示约定、计划或职责、义务要求即将发生的动作。
②be to do 安排将要干什么，有很强的计划性，有时=be going to
be to 表示客观安排或受人指示而做某事.
be going to 表示主观的打算或计划。
eg I am to play football tomorrow afternoon.
I'm going to play football tomorrow afternoon.
4．be about to do 表示“正要干什么?”，
表示即将发生的动作，不与表示将来的时间状语连用。
常与when 连用，when 此时意思： 就在这时，是并列连词
构成句型： ?be about to do ?when?.
eg. I was about to leave when it rained.
特别注意
（1）一般现在时表示将来，特别用于车、船、飞机等时刻表中安排好的。
The plane leaves tomorrow.(尽管有tomorrow, 但没有will ,be going to )
（2）某些瞬间动词“go, come, arrive ,leave ,start, begin, fly, take ”等用现在进行时表示将要发生的动作。
I’ve won a holiday for two to Floria. I ______my mum.
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A. am taking B. have taken C. take D. will have been
4. 现在进行时
1．表示说话时正在进行而尚未完成的动作或状态。
2．表示现阶段一直在进行的动作 ，但说话时不一定正在进行。
① I don’t really work here. I’m helping until the new secretary comes.
② Selecting a mobile phone for personal use is no easy task because technology___ so rapidly.
A. will have changed B. has changed C. is changing D. will change
③ ----Ann works very hard.
----In fact. I think she ______ just now.
A. studied B. is studying C. studies D. will stud
④ Please call again. Jim _____ a bath just now.
A. has had B. was having C. is having D. has
⑤My money ___. I must go to the bank to draw some of my savings out of before I’ve none in hand.
A. has run out B. is running out C. has been run out D. is being run out
⑥I can guess you were in a hurry. You _____ your sweater inside out.
A. had worn B. wore C. are wearing D. were wearing
特殊用性：
现在进行时可以表示一般将来时，常用于下列动词：go ,come, leave, begin, arrive ,return, fly, drive，take等。
eg We’re moving to the new building next week.
现在进行时与always, continually , constantly, never 等连用，表示厌恶或赞扬的感情色彩。 eg.You are always forgetting the important things.
1.You _____things about . Look, what a mess in you room!
A. always throw B. have always thrown C. are always throwing D. have always been thrown
2.You ______ television. Why not do something more active?
A. always watch B. are always watching
C. have always watched D. have always been watching
3．有些词不用于进行时态：表示“存在、所有、知觉、认应付，感情”等状态
存在： keep ,stay , remain , be, consist of , contain
所有： have ,belong to , possess, own , hold
知觉： sound(听起来)， look /seem /appear (看起来)， (看起来), smell（闻起来）,
taste（尝起来）, feel (摸起来) ， see , hear ,
认识： understand, know, suppose, remember, admit, forget, believe, think
情感：like, love, hate , prefer,
5.过去进行时
1．表示 过去某一时间正进行的动作 。通常有时间状语（从句），或由上下文表示。 ①.---Hey ,look where you are going?
-----Oh, I’m terribly sorry ._______.
A. I’m not noticing B. I don’t noticing C. I haven’t noticing D. I was n’t noticing ②.-----Hey ,what did I say?
-----I _________.
A. I’m not listening B. I was not listening C. I don’t listened D. I didn’t listen
2． 表示 过去某一阶段一直在进行的动作，但这个动作可以完，也可以不一定完成。 ③-----Why didn’t you join us last night?
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-----I _____ the live programs on the war between Iraq and the States.
A. watched B. was watching C. had watched D. have been watching
④----Why weren’t you at the meeting?
----I ____ for a long –distance call from my father in Australia.
A. waited B. was waiting C. had waited D. have been
⑤ Good heavens ! There you are ! We ____ anxious about you . We ____ you back much earlier all through the night.
A. are , expect B. were, had expected C. will be , are expecting D. have been , were expecting ⑥ ----You look tired.
----Yes. I non stop ____ until twelve o’clock.
A. am working B. was working C. has worked D. had worked
3．在简单句中有at that time, then , this time yesterday / last week, at 10 o’clock last night 等具体的时间状语用过去进行时态。
I first met Lisa three years ago . She ____ at a radio shop at the time.
A. has worked B. was working C. had been working D. had worked
特别注意：
与always连用，表示感情色彩。
My brother was always losing his key.
1. — Look! How wonderful my car is! Oh, Jack. What are you thinking about? Don’t you like it? — I’m sorry. I ______ any remark about it in time. I certainly think it’s smart.
A. wasn’t making B. don’t make C. won’t make D. didn’t make
2. To find the street where I lived in my childhood is no easy task because the city _____ so rapidly all these years.
A. is changing B. has changed C. will have changed D. will change
3. He ______ quite well, but he hasn’t had time to swim since this summer.
A. will swim B. have swum C. swam D. swims
4. Jimmy said that he would come to pick me up, but he ____by now.
A. hasn’t turned up B. doesn’t turn up C. won’t turn up D. hadn’t turned up
5. I’m terribly sorry for being late, but I _____ the wrong bus.
A. catch B. had caught C. caught D. catching
7. The truth, sir, is that the old man _______ across the road when my car hit him.
A. was to walk B. had been walking C. walked D. was walking
8. I really don’t think Rose will be upset, but I will go and see her in case she _____.
A. is B. does C. will be D. has been
9. The computers made by our company sell best, but several years ago no one could have imagined the role in the markets that they _________.
A. were playing B. were to play C. had played D. played
10. — Kate is in hospital.
— Oh, really? I _______. ________ visit her.
A. didn’t know; I’ll go and B. don’t know; I’ll go and
C. don’t know; I’m going to D. didn’t know; I’m going to
11. — Where _______ the guidebook? I can’t see it anywhere.
— I _______ it right here, but now it’s gone.
A. did you put; have put B. had you put; have put
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C. have you put; put D. were you putting; put
14. — Do you live in this city?
— No, we ______ it for holidays.
A. just visit B. just visited C. are just visiting D. have visited
15. — How is the old man now?
— Sorry, he ______ though they did all they could to save him.
A. was dead B. had died C. has been dead D. died
16.The lake will be further polluted unless some measures ______.
A. will be taken B. are taken C. were taken D. had been taken
17. I’m afraid it will be two months ______.
A. when I come back B. when I’ll come back
C. before I come back D. before I’ll come back
18.The workers _____ busily when the boss came to look for something he ______ in the office.
A. had worked, had left B. were working ; had left
C. working ; had left D. had worked; left
19.The notice ______ ―No smoking‖.
A. is told B. reads C. tells D. is read
6. 现在完成时
1．表示过去发生的某一动作对现在造成的影响或结果， 有时没有时间状语，有时有时间状语。 They have cleaned the classroom.(They cleaned the classroom and the classroom is clean now.)
2． 表示过去已经开始，持续到现在而且可能继续下去的动作状态。
He hasn’t given me any more trouble since then.
②----When did he go to America?
-----Oh, he ______ there since half a year ago.
A. went B. has been C. has gone D. was
③ Shelly _____ California for Texas and ____ there ever since. You can go and pay her a visit on your way to Mexico.
A. left, worked B. has left, had worked C. left, has worked D. has left , worked ④ Collecting stamps as a hobby ____ increasingly popular during the past fifty years.]
A. becomes B. became C. has become D. had become
⑤ ----How are you today?
---Oh , I ____ as ill as I do now for a very long time.
A. didn’t feel B. wasn’t feeling C. don’t feel D. haven’t felt
⑥ Rober ____ me his address the other day, but I’m afraid I ___ it .
A. had given, lost B. has given , have lost C. gave, have lost D. gives, lost
7.过去完成时
1表示在过去某一时刻或动作之前已经完成了的动作，即“过去的过去”。
请记住：by the end of +过去时间
be the time +从句（用一般过去时）引导的句子或主句用过去完成时）
①The film had already begun when I got there.
②They had left before I returned.
③We had finished the work by last month( by the time he came.)
2 表示由过去某一时间开始，一直延续到过去另一个时间的动作或状态。
I had been at the bus stop for 20 minutes when a bus finally came.
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3 用于hardly ?when ;no sooner ?than ?（一?.就?）等句子中。
Hardly had we arrived when she started complaining.
4 hope ,think expect ,intend ,mean ,suppose ,want ,imagine等，用于过去完成时，表示过去未实现的希望或意图。
I had hoped to be able to take my seat in all this noise without being found.
我本希望能乘着这些噪音不被发现地坐到位置上。（但实际上未实现）
5 It is the first time +从句（从句用现在完成时）；
It was the first time +从句（用过去完成时）。
It is the first time that I’ve been here.
It was the first time that he had ever spoken to me in such a tune.
6 用于对过去假设的虚拟语气中的从句。
If I had known your telephone number yesterday, I would have telephoned you .
1. The old man _____ two days after he had been sent to hospital.
A. died B. would die C. had died D. has died
2. Old McDonald gave up smoking for a while, but soon ______ to his old ways.
A. returned B. returns C. was returning D. had returned
3. I _____ my son _____ a doctor, but he wasn’t good enough at science.
A. hoped; would become B. had hoped; would become
C. had hoped; will become D. hope; will become
4. I _____ to take a good holiday this year, but I wasn’t able to get away.
A. hope B. have hoped C. had hoped D. hoped
5. Helen _____ her key in the office so she had to wait until her husband _____ home.
A. has left; comes B. left; had come C. had left; came D. had left; would come
8.现在完成进行时 构成：have /has been doing
表示过去某一动作状态一直持续到现在，也可能将持续下去。
----Isn’t it hard to drive downtown to work?
---Yes, that’ why I _____ to work by train.
A. have been going B. have gone C. was going D. will have gone
9.将来完成时： will / shall +have done
表示将来某一时间之前完成的动作，常与表示将来时间的状语连用，如：
by the end of+将来时间的短语,
by the time +从句（从句用一般现在时表示一般将来时），这时句子或主句应用将来完成时 eg.We will have finished the work by the time he comes back..
10.一般将来进行时； will be dong / shall be doing
表示将来某一时间正在进行的动作
What will you be doing this time tomorrow?
1.By the end of this month, we surely ____ a satisfactory solution to the problem.
A. have found B. will be found C. will have found D. are finding
2.The conference ____ a full week by the time it ends.
A. must have lasted B. will have lasted C. would last D. has lasted
1.He stepped into the office, _____ down and began to fill in the forms.
A. sitting B. to sit C. sat D. having it
2.She said she would telephone but we _____from her so far.
A.haven’t heard B.didn’t hear C.hadn’t heard D.won’t hear
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3.When I got to the cinema, the film____for ten minutes.
A.has begun B.had begun C.had been on D.was
4.I’ll go with you as soon as I____my homework.
A.will finish B.finish C.am finishing D.finished
5.If it_____tomorrow,I won’t go to the cinema.
A.will rain B.rains C.is raining D.rained
6.She is going to be a nurse when she_____up.
A.is going to grow B.grows C.growing D.grew
7.“这本书我已经买了三个月了。”，下列哪一句不对？
A.I have had this book for three months.
B.I have bought this book for three months.
C.I bought this book three months ago.
D.It is three months since I bought this book.
8.— Come in, Peter, I want to show you something.
— Oh, how nice of you! I _____ you _____ to bring me a gift.
A.never think; are going B.never thought; were going
C.didn’t think; were going D.had’t thought; were going
9.When I was at college I ___ three foreign languages,but I ___ all except for a few words of each.
A.spoke;had forgotten B.spoke;have forgotten
C.had spoken;had forgotten D.had spoken;have forgotten
10.The police found that the house _____ and a lot of things ____.
A.has broken into; has been stolen B.had broken into; had been stolen
C.has been broken into; stolen D.had been broken into; stolen
11.The volleyball match will be put off if it____.
A. will rain B. rains C. rained D. is raining
12.Mary _____ a dress when she cut her finger.
A. made B. is making C. was making D. makes
13.The students _____ busily when Miss Brown went to get a book she _____ in the office.
A. had written; left B. were writing; has left C. had written; had left D. were writing; had left
14. — Have you moved into the new house?
— No yet, the rooms _____,
A. are being painted B. are painting C. are painted D. are being painting
15. — We haven’t heard from Jane for a long time.
— What do you suppose ____ to her?
A. was happening B. to happen C. has happened D. having happened
16. — Do you know our town at all?
— No, this is the first time I _____ here.
A. was B. have been C. came D. am coming
17. — We could have walked to the station.It was so near.
— Yes, A taxi _____ at all necessary.
A. wasn’t B. hadn’t been C. wouldn’t be D. won’t be
18.If city noises ___ from increasing, people _____ shout to be heard even at the dinner table 20 years from now. A. are not kept; will have to B. are not kept; have to
C. do not keep; will have to D. do not keep; have to
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19.Tom _____ into the house when no one _____.
A. slipped; was looking B. had slipped; looked C. slipped; had looked D.was slippping; looked
20.The last time I _____ Jane she ____ cotton in the fields.
A. had seen; was picking B. saw; picking C. had seen; picked D. saw; was picking 几种时态的替代问题
A：一般现在时代替将来时 ：
除了在时间、条件、让步状语从句中用一般现在时代替将来时外，表示现在已安排好的未来事项，行程等活动也用一般现在时来代替将来时。如：
The museum opens at ten tomorrow. 博物馆明天10点开门。(实际上每天如此。)
B：一般现在时代替完成时：
句型 “It is ? since?”代替“It has been ? since ?”
It is (= has been) five years since we last met
C：一般现在时代替进行时：
在全部倒装句中都用一般现在时代替现在进行时。如： Look, here comes Mr. Li.
祈使句中的动词问题
高考题点击：
1. _____ it with me and I’ll see what I can do. (98 N)
A. When left B. Leaving C. If you leave D. Leave
2. _____ some of this juice --- perhaps you’ll like it. (2000 北京春季)
A. Trying B. Try C. To try D. Have tried
3. _____ at the door before entering, please. (01 北京春季)
A. knocked B. To knock C. Knocking D. Knock
4. _____ blood if you can and many lives will be saved.(2001上海)
A. Giving B. Give C. Given D. To give
1、现在时态
高考题点击：
Months ago we sailed ten thousand miles across this open sea, which ___ the Pacific, and we met no storms. （05辽宁卷）A．was called B．is called C．had been called D．has been called
2. I _____ ping-pong quite well, but I haven’t had time to play since the new year. (2001 N)
A. will play B. have played C. played D. play
3. Since I won the big prize, my telephone hasn't stopped ringing.
People _____ to ask how I am going to spend the money. （05湖南卷）
A. phone B. will phone C. were phoning D. are phoning
4. Selecting a mobile phone for personal use is no easy task because technology ___ so rapidly. (2001) A. is changing B. has changed C. will have changed D. will change
5. _____ my sister three times today but her line was always busy. （05北京春季）
A. I’d phoned B. I’ve been phoning C. I’ve phoned D. I was phoning
6. --- You haven’t been to Beijing, have you?
--- _____. How I wish to go there! (98 N)
A. Yes, I have B. Yes, I haven’t C. No, I have D. No, I haven’t
7. --- Hi, Tracy, you look tired.
--- I am tired. I _____ the living room all day. (98 N)
A. painted B. had painted C. have been painting D. have painted
8. Now that she is out of a job, Lucy_____ going back to school, but she hasn’t decided yet.（04北京） 9
A had considered B has been considering C considered D is going to consider 典型例题
(1) --- Do you know our town at all?
--- No, this is the first time I ___ here.
A. was B. have been C. came D. am coming
(2) --- Have you ____ been to our town before?
--- No, it’s the first time I ___ here.
A. even, come B. even, have come C. ever, come D. ever, have come （错）I have received his letter for a month.
（对）I haven't received his letter for almost a month.
2、过去时
高考题点击：
1. --- Nancy is not coming tonight.
--- But she _____! (98 N)
A. promises B. promised C. will promise D. had promised
2. My uncle _____ until he was forty-five. (2000 上海)
A. married B. didn’t marry C. was not marrying D. would marry
3. --- You haven’t said a word about my new coat, Brenda. Do you like it? (N2002)
--- I’m sorry I _______ anything about it sooner. I certainly think it’s pretty on you.
A. wasn’t saying B. don’t say C. won’t say D. didn’t say
4. As she ____ the newspaper, Granny ____ asleep. (95 N)
A. read … was falling B. was reading … fell C. was reading … was falling D. read … fell
5. The manager had fallen asleep where he ______, without undressing. （05安徽卷）
A. was laying B. was lying C. had laid D. had lied
6. The little girl ____ her heart out because she ____ her toy bear and believed she wasn’t ever going to find it. (02 北京)
A. had cried, lost B. cried, had lost C. has cried, has lost D. cries, has lost
7. — Hurry up! Alice and Sue are waiting for you at the school gate.
— Oh! I thought they ______ without me. (05江西卷)
A．went B．are going C．have gone D．had gone
3、将来时
高考题点击：
1. If a man _____ succeed, he must work as hard as he can. (95 上海)
A. will B. is to C. is going to D. should
2. --- You’ve left the light on.
--- Oh, so I have. _____ and turn it off. (2000 N)
A. I’ll go B. I’ve gone C. I go D. I’m going
3. By the time Jane gets home, her aunt _______for London to attend a meeting. (05天津卷)
A. will leave B. leaves C. will have left D. left
4. We were all surprised when he made it clear that he _____ office soon. (93 N)
A. leaves B. would leave C. left D. had left
高考题点击：
1. --- Can I join the club, Dad?
--- You can when you _____ a bit older. (94 N)
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A. getn B. will get C. are getting D. will have got
2. In such dry weather, the flowers will have to be watered if
they _____. (2001上海)
A. have survived B. are to survive C. would survive D. will survive
3. He will have learned English for eight years by the time he _____from the university next year.
A. will graduate B. will have graduated C. graduates D. is to graduate
4. It ____ long before we ____ the result of the experiment. (2002上海春季)
A. will not be, will know B. is, will know C. will not be, know D. is, know
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