that是個常見詞,用法廣泛.作為連詞,它可以引導不同種類的從句.現(xiàn)就此探討歸納如下：
一、that引導名詞性從句
所謂名詞性從句,指的是主語從句、賓語從句、表語從句和同位語從句.that引導名詞性從句時,它本身不作任何句子成分,也沒有任何詞義,只起連接作用.
1. that引導主語從句
可以將that引導的主語從句放在謂語動詞前面,也可在句首用形式主語it,而將that引導的主語從句后置.例如：
（1）That Mr King had been put into a women”s ward surprised his boss .
= It surprised his boss that Mr King had been put into the women”s ward .
金先生被安排在了女病房使他的老板很吃驚.
（2）That Professor Wang will give us a lecture tomorrow afternoon is known to all .
= It is known to all that Professor Wang will give us a lecture tomorrow afternoon .
大家都知道,王教授明天下午要給我們講課.
注意：that常在下邊的句型中引導主語從句：It is / was + 動詞的過去分詞 + that從句.例如：
（3）It is said that the book has been translated into several foreign languages .
據(jù)說,那本書已被譯成了幾種外語.
（4）It is reported that as many as 250,000 people lost their homes because of the earthquake .
據(jù)報道,多達25萬人因地震而無家可歸.
2. that引導賓語從句
引導賓語從句的that,在口語和非正式語體中?？墒÷?如果句中有兩個或兩個以上的賓語從句,則除第一個that可省略外,其它賓語從句中的that都不能省略.例如：
（1）He suggested (that) we should keep on trying .
他建議我們繼續(xù)努力.
（2）We must believe (that) each one of us is able to do something well , and that , when we discovered what this is , we must work hard at it until we succeed .
我們必須相信,我們每個人都能把每件事做好；而且我們領悟此事是何事之后,我們就必須努力做下去,直到成功為止.
3. that 引導表語從句
that引導的表語從句,一般位于句尾,that通常不能省略.例如：
（1）It seems that it is more difficult for women to get jobs than men .
似乎女人找工作比男人更難.
（2）The reason why so many people were killed in the big fire is that the building was built without any fire escapes .
這么多的人在大火中喪生,其原因是那座樓房里沒有太平門.
4. that引導同位語從句
同位語從句是對前面名詞的具體內容所作的詳細闡述.例如：
（1）We are surprised at the fact that the children did it on their own .
聽說孩子們獨立做那件事,我們感到吃驚.
（2）They expressed their hope that they would like to go to visit the Great Wall .
他們表達了他們想去參觀長城的愿望.
二、that引導定語從句
that引導定語從句時,是關系代詞,它可指人（相當于who , whom ）,也可指物（相當于which）.that在定語從句中可作主語,也可作賓語（作賓語時?？墒÷裕?當定語從句修飾的先行詞既有人又有物時,只能用that引導定語從句.例如：
1. This is the museum (that / which) they visited last month .
這就是他們上個月參觀的博物館.
2. They are going to the village that / which lies south of the mountain .
他們將去山南邊的那個村莊.
3. The man (that / who / whom) I shook hands with just now is one of my old classmates .
剛才和我握手的人是我過去的一位同班同學.
4. Do you still remember the things and persons that we talked about at the meeting last month ?
你還記得上月我們在會上談到的人和事嗎?
三、that用在強調句型中
強調句型的結構為：It is / was … that … .如果被強調的是人,可用who代替that.如果被強調的是時間狀語、地點狀語或原因狀語,則一般都用that.例如：
1. It was on July 30 that they decided to meet again .
就是在六月三十日他們才決定再一次見面的.
2. It is in the classroom that we usually have our classes .
我們通常是在教室里上課.
3. It was Ms King who / that pretended to be a man in order to get a job .
為找工作而女扮男裝的是金女士.