1、That 在英语中是一个使用频率很高的词。它可用作代词、连词、关系代词等，有时可以省略。但在以下几种情况下 that 不可省略。一、that 用作代词，指上文提到的人或事物(单数名词) ，且需一个后置定语来修饰，此时 that 不可省Their cotton output of 1997 was double than that of 1987.Marys handwriting is far better than that of Peter .二、that 用作连词，在 so.that, such.that, in order that 等引导的状语从句中，that 不可省。They st
2、arted so early that they might arrive in tim e.It is such a heavy box that nobody can move it.He worked hard in order that he might catch up with the others.三、that 用作连词，引导主语从句时，当它放在主句谓语动词之前时，that 不可省。That he came late made his teacher angry.That she was chosen made us very happy.如用 it 作形式主语，把从句置于谓语动
3、词之后时，that 可以省略。例如：It is a pity(that) he has made such a mistake.It is obvious(that) he is right.四、that 用作 连词，引导表语从句和同位语从句时，that 不可省。The news that our team has won the match is true.My idea is that we should get more comrades to do t he work.五、that 用作连词，引导宾语从句时，如主句的谓语动词是及物动词 make,find,see等时，且后有宾语补足语时
4、，that 引导的从句可置于宾语补足语之后，用 it 作形式宾语，此时 that 不可省。He made it clear that he was not interested in this subject.当 that 宾语从句的主语是非谓语动词或是主语从句时，that 不可省略。例如： The doctor said that taking exercise was the best way of losing weight. 医生说运动是最好的减肥方式。 The old lady then explained that what she was looking for was a pa
5、ir of gloves for a girl. 老太太然后说她寻找的是一双女孩子戴的手套。 六、that 用作关系代词，引导定语从句时，当它作为从句的主语时，that 不可省。All that have to do is to practise every day.Thats the same man that asked me for money yesterd ay.但如 that 作从句的宾语时， that 可省略。The letter(that) I received was from my father.七、在强调句型 It is/was.that 结构中，that 不可省。It is English that Professor Li teaches us.It was in Shanghai that I saw the film.
