連詞that在引導(dǎo)名詞性從句時(shí)，本身無意義，在從句中只起連接作用，不擔(dān)任任何句子成分，不含有疑問語氣，有時(shí)可以省略。下面按名詞性從句的語法分類，對(duì)that在其中的用法進(jìn)行比較和分析。
　　
　　一、主語從句
　　
　　(1)that在主語從句中只是引導(dǎo)詞的作用，不作甸子成分，不能省略。
　　例如：That you are coming to London isthe best news I have heard this long time.
　　(2)如果主語從句太長，可以用it作形式主語代替that主語從句，以達(dá)到平衡句子的作用。此時(shí)的that也不能省略。
　　例如：
　　It’s unlikely that he’ll come.
　　It’s a fact that they won the game.
　　It seems that he has known the truth.
　　It’s reported that there will be a stormtomorrow.
　　
　　　二、表語從句
　　
　　　That在引導(dǎo)表語從句時(shí)沒有詞義，不含疑問意義。在口語中，有時(shí)可以省略。
　　例如：
　　The trouble is(that)they have lost theirway.
　　Her wish is that she could lose weightsoon.
　　
　　　三、同位語從句
　　
　　　That在引導(dǎo)同位語從句時(shí)無詞義，不作句子成分。不含疑問意義。
　　例如：
　　The news that he went abroad is nottrue.
　　Word came that Professor Lee wouldcome to our school.
　　The fact that women can word as well asmen is clear.
　　
　　　四、賓語從句
　　
　　　That在引導(dǎo)賓語從句時(shí)，只起引導(dǎo)詞的作用，在句中不做語法成分。在口語中和非正式文體中可以省略。
　　例如：
　　I’ll prove to the world that he was right.
　　She always complains that he is down onher.
　　這類從句一般不能作介詞賓語，但是在in，but，except，besides等少數(shù)介詞后可以使用，形成固定搭配。
　　例如：
　　I’ll go with you，except that I have toword that day.
　　Men differ from brutes in that they earlthink and speak.
　　That引導(dǎo)的賓語從句不能省略的情況：
　　1.　如果賓語從句過長，可以用it充當(dāng)形式賓語代替賓語從句。這種結(jié)構(gòu)中That不能省略。
　　I think it wrong that he didn’t tell thetruth.
　　We took it for granted that he will takeover his father’s job.
　　I hate it when people talk with theirmouths full.
　　2.　幾個(gè)賓語從句并列時(shí)，從第二個(gè)開始的賓語從句中的That不能省略，或者句子結(jié)構(gòu)很復(fù)雜有多個(gè)狀語時(shí)，或者謂語動(dòng)詞與That之間有插入語時(shí)，That不能省略。
　　例如：She promised(that)she would come andsee him sometimes，and that she would neverforget him.
　　We decide，as he has suggested.that wewill start out tomorrow.
　　
　　作者單位：河南省沈丘縣第一高級(jí)