1．it引导的强调句型，通常形式为：It＋be＋被强调部分＋that／who＋其它。这种强调句由普通陈述句转换而来，用来强调句子的主语、宾语或状语。例如：
Karl bought Marva a bicycle on her birthday．卡尔在玛瓦生日那天给她买了一辆自行车。
It was Karl that／who bought Marva a bicycle on her birthday．（强调主语）
It was Marva for whom Karl bought a bicycle on her birthday．（强调间接宾语）
It was a bicycle that Karl bought Marva on her birthday．（强调直接宾语）
It was on her birthday that Karl bought Marva a bicycle．（强调状语） ______ she first heard of the man referred to as a specialist．
A）It was from Stephen
B）It was Stephen whom
C）It was from Stephen that
D）It was Stephen that （B4．1990．1－48，C对。强调状语）她是从斯蒂芬那儿第一次听说被称为专家的那个人。 It was the training that he had as a young men ______ made him such a good engineer．
A）that
B）has
C）what
D）later
（1999年全国大学生英语竞赛初赛试题，强调主语）A对。正是他年轻时候接受的训练使他成为一名优秀的工程师。（试比较： The training that he had as a young man made him a good engineer．）
但是这种句型通常不用来强调表语，例如我们不说：＊It is a teacher that he is． 2．注意区别强调句中的that／who分句与定语从句：
It was the student that／who asked the silly question．是一个学生问了这么一个愚蠢的问题。（分裂句）
He was the student who asked the silly question．他就是问了这么一个愚蠢问题的学生。（划线部分是定语从句）
3．在含有until时间状语的否定句中，如果强调时间状语，就成了it is ／was not until．．．that．．．．例如：
We did not begin studying French until we entered university．我们进了大学才开始学法语。 要强调until we entered university，就成了：
It was not until we entered university that we began studying French． ______ the 18th century that man realized that the whole of the brain was involved in the workings of the mind．
A）During
B）In
C）It was until
D）It was not until D对。直到十八世纪，人们才意识到：心理活动与整个大脑有关。
4．这种句子也可能是疑问句：
Why is it that you hate winter？你究竟为什么不喜欢冬天？
How was it that you missed such a wonderful lecture？你怎么会错过这么精彩的报告？
When was it that they went abroad？他们什么时候出国的？
5．这种结构还常常出现在谚语里，表示"无论怎样……都不……"，是一种反语式的强调用法；原来是莎士比亚时代的用法，所以现在容易出现理解上的错误。例如：
It's a wise father who knows his own child．无论多聪明的父亲也不见得了解自己的孩子。 It's an ill wind that blows nobody（any） good．此失则彼得，没有使所有的人都受害的坏事。
广西大学梧州分校/黄积达