如题所述
that的用法，要看它用于什么样的从句中：
定语从句：指代物或人，作主语时，不可省略；作宾语时，可省略。当先行词是人和物时，一般不省略。
名词性从句包括：主语从句，宾语从句，表语从句和同位语从句。在以上名词性从句中，只有在宾语从句中菜可以省略；其他情况下，都不可省略。
强调句型：It is ...that...中的也不能省略
扩展资料
在一般情况下，宾语从句中的that只起引导作用，在句中不做任何成分，没有实际意义，通常可以将其省略。例如，
I think (that)he’ll be all right in a few days.
Current trends indicate (that)transportation is becoming cleaner,faster and safer.
但是，that在引导宾语从句时并非在任何情况下都可以省略。在以下情况中，that不能省略。
（1）and 连接两个或两个以上的宾语从句时，第一个that可以省略也可以不省，但其它不能省略，以免产生误会：
Galileo’s observations show (that) Copernicus, another great astronomer, was right and that the earth moves around the sun, not the other way around.
(2) that引导的宾语从句放在except ,but 等介词后面的时候,that不能省略.
He is a good student except that he is a little careless.
(3) that 引导的宾语从句放在句首起强调作用的时候,that不能省略.
That he ever said such a thing I simply don’t believe.
(4) 主句谓语动词和that引导的宾语从句之间有插入的时候,that不能省略
Everyone could see , I believe , that Tom was really afraid .
(5) it 作形式宾语时,that 引导的宾语从句中的that不能省略.
We thought it strange that Xiao Wang did not come yesterday.
(6) 在对话中简短回答时,如果that引导的宾语从句独立出现,that不能省略.
---What did he say ?
---That he won the first prize in the game .
(7) 在可接双宾语动词后that引导的宾语从句作直接宾语的时候,that不能省略.
The foreign friend tells us that Chinese is one of the most difficult languages to learn .
(8) 在that引导的宾语从句之前或之后紧接着一个状语的时候,that不能省略.
He suddenly caught sight of the boy and realized at once that he had seen him before.
(9) 在直接引语中,that引导的宾语从句与主句隔开的时候,that不能省略,.
“I’m sorry to say,” he said ,“that you are not the suitable person for the work.”
1、that引导的由陈述句转化而来，用于陈述一件事。在口语中，that常可省略。例如：
We know (that) he is a kind boy.
我们知道他是个善良的孩子。
Jim said (that) he had a fever yesterday.
吉姆说他昨天发烧了。
2、当主句的主语为，谓语动词是think、believe、guess、imagine等表示“观点、信念、推测”等心理活动的词时，that从句的否定词常常要转移到主句中。例如：
I don’t think (that) it will snow this weekend.
我想这个周末不会下雪。
3、当主句是时，从句的时态可视情景而定；当主句是，从句的时态也要使用相应的过去时态；但是当从句所表达的是客观真理或客观事实时，从句的时态不受主句限制，使用一般现在时。例如：
I guess (that) she went there with Mary.
我猜她和玛丽一起去那儿了。
扩展资料
在以下情况中that不能省略：
1、当句中的动词后接多于两个由that引导的宾语从句时，第一个that可省，但后面的that不可省。
例句：He said (that) you were too young to understand the matter and that he was asked not to tell you.
他说你太年轻了，不明白这件事，他被要求不要告诉你。
2、当主句的谓语动词与that宾语从句之间有时，that一般不可省。
例句：Just then I noticed, for the first time, that our master was wearing his fine green coat and his black silk cap.
3、当that从句是中的直接宾语时，that不可省。
例句：I can’t tell him that his mother died.
就在这时，我第一次注意到我们的主人穿着他那件漂亮的绿外套，戴着他的黑丝帽。
注意事项：许多带复合宾语的句子，that引导的宾语从句经常移到句子后部，而用it作形式宾语。
本回答被网友采纳注:宾语从句中that一般情况可省 ,但that在引导宾语从句时也并不是任何情况下都可以省略。在以下情况下，that不能省略。
1． Everybody could see what happened and that Tom was frightened.(and连接两个宾语从句，that宾语从句放在and的后面时，that不能省略。)
大家都会看出所发生的事情并知道Tom非常害怕。
2．I know nothing about him except that he is from the south.(that引导的宾语从句作介词宾语时，that不能省略。)
对他我一无所知，只知道他是南方人。
3．That he ever said such a thing I simply don’t believe. (that从句位于句首时，that不可省略。)
我简直不相信他曾说过这样的话。
4． We decided, in view of his special circumstances, that we would admit him for a probationary period. (主句谓语动词与that从句之间有插入语，that不可省略。)本回答被提问者采纳
宾语从句与主句之间需要有连词进行连接，that可以省略。
可以说基本上在非正式文体，that都可以省略
如
I
know
that
you
are
a
student..that
可以省略
I
know
that
is
your
book.
我知道那是你的书。that
在宾语从句中做主语，that不可以省略。
