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; 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。
(3)学生写作实例
实例 1：Many; people，; if; not; most，; are; strong; believer; in; the; claim; that; regard; children; go; to; work; as; completely; wrong，while; others; hold; the; opposite; opinion.
修改建议：it; is; completely; wrong; for; children; to; go; to; work.
实例2：They; have; to; complete; their; homework; conscientiously; within; limited; time; and; difficult; to; discover; the; problems; in; studies.
修改建议：thus; it; is; difficult; to; discover; their; problems; in; study.
实例3：College; graduates; are; difficult; to; find; jobs.
修改建议：It; is; difficult; for; college; graduates; to; find; jobs.
实例4：Parents; realise; the; needs; of; their; children; is; extremely; important.
修改建议：It; is; extremely; important; for; parents; to; realise; the; needs; of; their; children.
It; is; extremely; important; that; parents; realise; the; needs; of; their; children.
（三）it作形式主语的特征分析
根据以上对it作形式主语的句型结构的解析，对雅思写作范文、尤其是官方考官范文的分析，以及对学生写作过程中出现的it使用状况的详细解读可知： 相比较于名词性从句、定语从句、状语从句的复杂性和多边性，it作为形式主语的句式结构可谓简明扼要，学生掌握起来应该说是得心应手的。
（四）不能正确使用it形式主语的原因
在信息编排时，英语句子遵循“end; focus”的原则，即旧信息在前，新信息在后 “old; information+new; information”; 但是，当句子主语结构较长，容易使句子产生“head; weight”的感觉时， 句子结构则遵循“end; weight”的原则，即，把较长的主语全部置于句子尾部。前面空掉的主语位置用it来代替，担当形式主语的功能。
而汉语并不具有这类明显的特征，学生对英汉两种语言结构差异知之甚少，或者略有所知，在真正的运用中，也未必能够正确的体现出来。多数学生都本着汉语式的思维，一遇到“某人做某事是怎么样的/是什么”就习惯性地写成t"
三、总结；
建议学生在雅思学习中，采取步步为营的四步走战略战术，循序渐进：首先，记住句型结构; 其次，模仿写作; 之后，进行独立创作; 最后，形成属于自己的 模板句型。作为雅思写作学习中可控制的因素，我们可以培养句式运用的习惯，使习惯称为自然。为了我们雅思的学习这个努力是值得 的，it; pays; in; the; long; run.
