形式主语

当主语是不定式、动名词、或者从句时，对句子进行倒装可以避免由于主语过长而引发的“不美观”。倒装的方式是将原句中的主语后置，并且在原主语位置上添加it占位。例如：

It is my pleasure to address the meeting. （不定式）
To address the meeting is my pleasure.

It is no good reading in dim light. （动名词）
Reading in dim light is no good.

It is extremely obvious that she has been lying about her identity. （从句）
That she has been lying about her identity is extremely obvious.

以上三组例句中的每个句子均没有语意上的区别，在GMAT考试中也无优劣可言，仅仅是一种在语形上的变化。当然，形式主语也可以用于使役动词的身后，例如：

Cherry made it possible to attend the meeting.
Cherry made to attend the meeting possible.
Cherry made possible to attend the meeting.

这个三个例句在语意上也完全相等。