关于专升本英语，同学们在做完形填空题时，最忌在对文章似懂非懂的状态下，仅凭孤立的语法和词汇关系，草草圈定答案。我们应持的态度是，务必注意对文章主旨的`理解，注意对上下文线索的追踪回顾，注意前后照应，并将语境、语义与语法、词汇的搭配，通盘进行考虑。说起来容易，做起来难，小编先给大家总结一下完型填空中经常考的重点句型，大家学习学习，用来备考英语完型填空。
一、It 作形式主语
1、It is + 名词/形用词/过去分词 + that 从句 (主从) = that 从句 (主从) is +名词/形用词/过去分词
It is well known that + 句子(众所周知)
It is obvious that + 句子 (明显的)
It is apparent that + 句子 (显然的)
例句：It is well known that diamonds are the hardest substance.
例句：It is universally acknowledged that trees are indispensable to us
全世界都知道树木对我们是不可或缺的.
例句：It is common knowledge that honesty is the best policy.
2. It is + 形容词/过去分词/名词 (for sb.)+ to do …
例句： It is hard (for me)to finish the work in three days.
It is an honor to meet you.
was said/reported/ thought/believed + that从句(主从) 据说/报道/认为…
Sb. was said/reported/ thought to do …
例句：It was said that he had been killed in the accident.
此句子可以转化为：He was said to have been killed in the accident.
4. It took/ will take sb. + time to do … 某人花费时间干…
例句：It took me 10 days to finish my paper.
二、It 表示时间的常用句型
is/has been+一段时间+since... "自从...已有多久"
since后的从句用一般过去时
It has been two weeks since he left
他已经离开了两个星期了
was+一段时间+before... "在...之前过了多长时间"
before 后的从句用过去完成时
It was three years before he had finished his research
在他完成他的研究之前已经过去三年了
will be+一段时间+before... "过了多久才..."
before后的从句用一般现在时
It will be two days before she arrives at Britain
两天后她才会到达英国
