that可以引导名词性从句、定语从句,其具体用法如下：
一、that引导名词性从句时(即主语从句、宾语从句、表语从句、同位语从句),在从句中无具体含义,只起连接作用,而且在从句中也不作任何句子成分.它所引导的从句的句子结构和意义是完整的,而且从句一般是陈述一个事实.
例如:
①That she was able to come made us very happy.
她能来使我们很高兴.
②The news that our team has won the match is true.
我们队赢了这场比赛的消息是真的.
③The reason he didn't come was that he was ill.
他没来的原因是他病了.
当that引导的主语从句或宾语从句太长时,常用it作形式主语或宾语而把that从句放在后面.如:
①It is well—known that the earth is round.
众所周知,地球是圆的.
②We find it necessary that we practise spoken English every day.
我们发现每天练习英语口语很有必要.
注意：
that引导的主语从句,表语从句以及同位语中,that不能省略.that引导的宾语从句,一般可以省去that,但在下面情况中不能省略——
1.在suggest,order等表示命令、请求、建议等动词后的宾语从句中,不能省；
2.由and或but所连接的两个引导的宾语从句时,第一个从句中的that可以省,第二个从句中的that不能省；
3.that引导的宾语从句,如果从句中还有其他状语从句,引导宾语从句的that不能省略.
Tell him that if he is at home,I'll call to see him.
二,that引导定语从句要注意以下几点:
1.定语从句中缺主语,修饰人时用who /that,修饰物时用which /that引导.如:
Is this the factory which /that makes TV sets
The man who /that visited our school is from Australia.
2.从句中缺宾语,修饰人时用 who /whom /that或省略引导词;修饰物时用which /that或省略引导词.如:
Gone are the days which /that we spent together in the village.
He is the man who /whom /that I think to be worthy of our praise.
3.用that不用which的七种情况:
①先行词前有形容词最高级或序数词修饰时,用 that不用which引导.如:
This is the best place that I have ever visited.
②先行词为little,much,all,none,few,(the)one,something,everything,nothing,anything等不定代词时,用that引导.如:
There is nothing in the world that can frighten him.
③先行词既有指人的名词又有指物的名词时,用 that引导.如:
He told us about the people and the cities that he had visited.
④先行词前有any,all,no,few,every,some,little,much,(the)very,(the)only,(the)last等词修饰时,用 that引导.如:
This is the very coat that I need.
⑤先行词为which时,为了避免重复,用that引导.如:
Which is the book that you bought yesterday
⑥先行词在从句中作表语时,常用that引导.如:
Shanghai is no longer the city that it used to be in the 1930's.
⑦当主句是There be...句型时,用that引导.
There are two tickets for the film that are for you two.