一、引出开头
1：It is well-known to us that……（我们都知道……）==As far as my knowledge is concerned, …（ 就我所知…）
2：Recently the problem of…… has been brought into focus. ==Nowadays there is a growing concern over ……（最近……问题引起了关注）
3：Nowadays（overpopulation）has become a problem we have to face.（现今，人口过剩已成为我们不得不面对的问题）
4：Internet has been playing an increasingly important role in our day-to-day life. It has brought a lot of benefits but has created some serious problems as well.（互联网已在我们的生活扮演着越来越重要的角色，它给我们带来了许多好处但也产生了一些严重的问题）
5：With the rapid development of science and technology，more and more people believe that……（随着科技的迅速发展，越来越多的人认为……）
6：It is a common belief that……==It is commonly believed that……（人们一般认为……）
7：A lot of people seem to think that……（很多人似乎认为……）
8:It is universally acknowledged that + 句子（全世界都知道...）
…… …… 余下全文
（
是B与S的夹角）看，磁通量的变化
可由面积的变化
引起；可由磁感应强度B的变化
引起；可由B与S的夹角
引起；也可由B、S、
在裸金属导轨上向右匀速运动过程中。