(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; right; to; judge; whether; children; working; is：“wrong”; or：“valuable”.; (Cambridge; 3，; P164，; Task; 2)
D.; …，; it; is; important; to; remember; that; children; 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; ang; 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; 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。
