It 的用法 1： it 做形式主语，不定式to do 或that 引导的句子做真正的主语 例句: It is important for us to protect environment. 保护环境对我们来说是很重要的。〔it 做形式主语，真正的主语是to protect environment〕即 to protect environment is important for us 是本句，但这样显得头重脚轻，所以用it 做形式主语. 例句: It is common knowledge that science and technology is the first productive force.( it 做形式主语，that 引导的句子做真正的主语 2：it 做形式宾语，不定式to do 或that 做真正的宾语 例句：He thinks it very hard to master a foreign language.他认为掌握一门外语是很难的。〔he做主语，thinks 做谓语，it 做形式宾语，very hard 做宾补，to master a foreign language 做真正的宾语，即He thinks to master a foreign language very hard. 例句：He thinks it very essential that he should have a decent job.他认为他应该有一份体面的工作是很必要的即He thinks that he should have a decent job very essential. 3: it 用于强调句，其构造是it is \was+强调局部+that 例句：It was his carelessness that caused his fatal failure.正是他的粗心导致了他的致命失败。〔强调his carelessness,做caused的主语,即强调主语〕 例句：It was in the cinema that I came across my former English teacher.在电影院我巧遇我的前任英语教师。 (强调地点状语in the cinema) 强调句去除it is 和that 这三个词仍然还是完好的句子 4 It引导时间的三种句型 1：It is +一段时间+since 从句〔从句用一般过去时〕 例句：It is a decade since we became friends.自从我们成为朋友已经有十年了。 2: it was +一段时间+before 从句〔从句用一般过去时〕 例句：It was several weeks before he found that his precise painting was missing.过了好几周他才发现他的珍贵画不见了。 3 ： it will be +一段时间+before 从句〔从句用一般如今时〕 例句：It will be a long time before China becomes a developed country.在中国成为兴旺国家之前将需过很长一段时间。 语法单项选择 1 It is his ability that _________________. A he has become a general manager B makes him become a general manager C why he can become a general manager D for which he becomes a general manger 2 ________is very import for her ____________. A It , has complete her work in time B It , because she has to complete her work in time C It , to complete her work in time D There , to complete her work in time 3 I think _____________________. A it is very crucial to save money B it very crucial saving money C it very crucial save money D it very crucial to save money 第 1 页 4 It was his courage ______________. A that made him stand out B that he stood out C why he stood out D helped him stand out 5 It _______ten years __________he became a teacher. A was , since B is, after C is, before D is , since 6 It __________many hours __________his mother arrives home. A will be ,before B is , before C was , since D will be , before 7 It ___________two years _________he found that he had caught the liver cancer. A was, before B was,since C has been ,when D is,before 8 It was ____________that_____________. A because he spared no efforts to study ,made him become a top student. B because of his diligence that made him become a top student. C his diligence ,he became a top student D his diligence, made him become a top student. 语法填空 1 It is essential for students ________(keep)healthy. 2 I feel ________very necessary for me to help her. 3 It is only in this way _________we can achieve the instant fame. 4 I feel __________very important _______we keep practicing English everyday. 5 It __________two days __________the meeting ends. 6 It _________two weeks _________we knew each other 7 It __________a long time ________we become successful actors. 8 It ___________ five days ________ we arrived in Macao. 答案及解析〔单项选择〕 1 B 【 解析】 强调句，因为it is his ability that 强调的是名词his ability ,只能做makes 的主语 2 C 【解析】 it 放句首做形式主语，只能to do 或that 引导的句子做真正的主语 3 D 【解析】it 放think 后做形式宾语，后面to do 做真正的宾语 4 A 【 解析】 强调句，强调主语 5 D 【解析】it is +一段时间+since 从句 6 D 【解析】it will +一段时间+before 从句〔从句用一般如今时态〕 7 A 【解析】it was +一段时间+before 从句〔从句用一般过去时态〕 8 D 【解析】强调句 his diligence 做made 的主语 答案及解析〔语法填空〕 1 to keep 【解析】it 放句首做形式主语，to do 做真正的主语 2 it 【解析】it 放feel 后做形式宾语，to help her 做真正的宾语 3 that 【解析】强调句，强调局部only in this way 做方式状语 4 it ,that 【解析】it 做feel 的形式宾语,后面是句子不是不定式 5 will be ,before【解析】ends 是一般如今时，只合适it will be+一段时间+before 从句 6 is ,since【解析】knew 是一般过去时态，根据意思，只合适it is +一段时间+since 从句 第 2 页 本文来源：https://www.wddqw.com/doc/b2013e386f175f0e7cd184254b35eefdc8d315e4.html