1 . in /after
We'll meet again_two weeks.两周后我们还会再见。 in+时间段:表示将来，即:在多长时间以后。常用将来时，且是非延续性动词。
after+时间段:表示“过了段时间以后”，常指从过去某时算起的一段时间之后，所以常用于一般过去时。
而after+时间点，表示“某刻以后”，常用于将来时。 in /after
2.for/by
for+时间段，表示“共计多久了”。常用于完成时态、或完成进行时态。表示从过去某时间点到说话时完成的动作，或一直延续的动作。
by+时间点，表“截止到某时”， 常用于完成时态。
I have learned 1000 English words___now.
到现在为止，我已经学了一千个单词了。
By
He had learned 2000 English words ___the end of last year.
到去年年底为止,他已经学了两千个英语单词了。 By
4. I bought some food and left the store a few minutes.我买了一些食物，几分钟后我离开了那家商店。
After
5.— How long have you learned English?
你学习英语多久了?
--- ___about five years.学了约五年了 For
6. Don't stay out____midnight.
不要在外面呆到午夜以后。
beyond+时间点，表示“(时间)过了...... ,比...... 晚，迟于......”的意思。
7. It's over three week____she left home.
自从他离家以来，已经有三周多了。
since+时间点，表示自从什么时间以来。
8. I have learned English_____ 10 years.
我已经学英语十年了。
for+时间段，表示“共计多久了”。常用于完成时态、或完成进行时态。用来修饰从过去某时间点到说话时完成的动作，或一直延续的动作。
9. I have learned English______10 years ago.
自从+年前以来我一直学习英语。
since+时间点，表示自从什么时间以来。10years ago是时间点，不是时间段。
用after、since、for、by、in、beyond填空
1、We'll meet again____two weeks.
2、I have learned 1000 English words___now.
3、He had learned 2000 English words ___the end of last year.
4、I bought some food and left the store ___ a few minutes.
5.— How long have you learned English? ___ about five years.
6. Don't stay out____midnight.
7. It's over three week____she left home.
8. I have learned English_____ 10 years.
9. I have learned English______10 years ago
第二篇：Since 和 for 的用法及区别
Since 和 for 的用法及区别：
一， since 的四种用法
1， since + 过去一个时间点（如具体的年、月、日期、钟
点、 eg. 1990 , last month , half past six
I have been here since 1990. 1990起，我一直在这儿。 2， since+ 一段时间+ago
I have been here since five months ago。自从五个月前，
我已经在这儿了。
3， since+从句
Great changes have taken place since you left. 自从你走
后，已经发生了很大的变化。
4，It is +一段时间+since 从句
It is two years since I became an English teacher. 我成为
英语老师有两年了。
Since 和 for 区别
Since +时间点，具体时间，“ 自从、、、以来，从、、、以后” 用来说明动作起始时间
I have been in Beijing since 2010.
For + 时间段 ，用来说明动作延续时间长度 ，因此句中的谓语动词，也应该是延续性动词。
I have been in Beijing for one year。
We have learnt English for about three years.
I have been here for 3 days. (对)
I have arrived here for 3 days.（误）
延续性动词和终止性动词的概念
英语中，动词按其动作发生的方式、动作发生过程的长短，可分为延续性动词和终止性动词。
延续性动词表示能够延续的动作，这种动作可以延续下去或产生持久影响。如：learn, work, stand, lie, know, walk, keep, have, wait, watch, sing, read, sleep, live, stay等。
终止性动词也称非延续性动词、瞬间动词或短暂性动词，表示不能延续的动作，这种动作发生后立即结束。如open, close, finish, begin, come, go, arrive, reach, get to, leave, move, borrow,buy等。
一、延续性动词的用法特征
1.延续性动词可以用于现在完成时，其完成时态可与表示"段时间"的状语连用。表示"段时间"的短语有：for two years, during the past three years, since last year, how long等。如：I have learned English since I came here.自从我来到这儿就学英语了。
2.延续性动词不能与表示短暂时间的"点时间"状语连用。如：It raind at eight yesterday morning.(误) rain为延续性动词，而at eight表示"点时间"，前后显然矛盾。如果用延续性动词表示一瞬间的动作，可以借助come, begin, get等终止性动词来表示。上句可改为：It began to rain at eight yesterday morning.(正)又如：
-When did you get to know Jack?
-Two years ago.
-Then you've known each other for more than two years.
-That's right.
二、终止性动词的用法特征
1.终止性动词可用来表示某一动作完成，因此可用于现在完成时。如：
The train has arrived.火车到了。
Have you joined the computer group?你加入电脑小组了吗？
2.终止性动词表示的动作极其短暂，不能持续。因此，不可与表示一段时间的状语连用(只限肯定式)。如：
(1)他死了三年了。
误：He has died for three years.
正：He has been dead for three years.
正：He died three years ago.
正：It is three years since he died.
正：Three years has passed since he died.
(2)他来这儿五天了。
误：He has come here for five days.
正：He has been here for five days.
正：He came here five days ago.
正：It is five days since he came here.
正：Five days has passed since he came here.
句中终止性动词转换为相应的延续性动词，如上面两例中的第一种正确表达方式。下面列举几例：leave→be away, borrow→keep, buy→have, begin/start→be on, die→be dead, move to→live in, finish→be over, join→be in/be a member of, open sth.→keep sth. open, fall ill→be ill, get up→be up, catch a cold→have a cold。