一、引言
在看学生的雅思写作文章过程中，总会看到这样的文字，“College graduates are difficult to find jobs. ”，“Parents realise the needs of their children is extremely important. ”，“Students cannot focus on their study because of tiredness is a fact. ”， “Clearly, rush hours emerges in the early morning as well as early evening which is most busy in a day as a whole in London.” 这几个句子，虽然长短不一，结构不同，话题各异，但是，学生对形式主语it的驾驭能力的欠缺，是可见一斑的。
二、形式主语
（一）什么是形式主语
作为形式主语的it并无实际语义，是为满足语法上的需要，避免句子头重脚轻，它代替的`是句子的逻辑主语。
（二）形式主语it所在的句型类别
1、作不定式的形式主语
（1）句型
It is + a pity/a pleasure + to do sth.
It is + wrong/right/wise/cruel/naughty/selfish + of sb. + to do sth.
It is + necessary/hard/important/difficult/possible/common + for sb. + to do sth.
（2）雅思范文写作实例
A. Beyond this, it is also of paramount importance to use theaters and museums as the “social classroom" of culture and history education.
B. I think it is by no means pointless in any way to try to keep traditions alive with technology (Cambridge;3,;P162,;Task;2)
C. It is difficult to say who has the rightto judge whether children working is “wrong” or “valuable”. (Cambridge;3,;P164,;Task;2)
D. it is important to remember that need to develop skills other than intellectual ones and …(Cambridge;3,;P168,;Task;2)
E. Finally, I think that it is also important to remember that children need to relax as well as work. (Cambridge;3,;P168,;Task;2)
F. Because people interpret happiness for themselves in so many different ways it is difficult to give and definition that is true for everyone.(Cambridge;4,;P165,;Task;2)
G. It is quite common these days for young people in many countries to have a break for studying after graduation from high school.(Cambridge;5,;P165,;Task;2)
H. They may think that it is better to continue in a particular job or to do sth completely different from a university course. (Cambridge;5,;P165,;Task;2)
据本人统计，剑桥官方的雅思真题（剑3—剑8）几乎每一篇Task2考官范文中，都有所使用，甚至在有的文章中出现三次之多。