that是个常见词,用法广泛.作为连词,它可以引导不同种类的从句.现就此探讨归纳如下：一、that引导
名词性从句所谓名词性从句,指的是
主语从句、宾语从句、表语从句和同位语从句.that引导名词性从句时,它本身不作任何句子成分,也没有任何词义,只起连接作用.1.that引导主语从句可以将that引导的主语从句放在
谓语动词前面,也可在句首用形式主语it,而将that引导的主语从句后置.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惊.（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,王教授明天下午要给我们讲课.注意：that常在下边的句型中引导主语从句：It is / was + 动词的
过去分词 +
that从句.例如：（3）It is said that the book has been translated into several
foreign languages .据说,那本书已被译成了几种外语.（4）It is reported that as many as
250,000 people lost their homes because of the earthquake
.据报道,多达25万人因地震而无家可归.2.that引导宾语从句引导宾语从句的that,在口语和非正式语体中常可省略.如果句中有两个或两个以上的宾语从句,则除第一个that可省略外,其它宾语从句中的that都不能省略.例如：（1）He
suggested (that) we should keep on trying .他建议我们继续努力.（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
.我们必须相信,我们每个人都能把每件事做好；而且我们领悟此事是何事之后,我们就必须努力做下去,直到成功为止.3.that
引导表语从句that引导的表语从句,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难.（2）The reason why
so many people were killed in the big fire is that the building was
built without any fire escapes
.这么多的人在大火中丧生,其原因是那座楼房里没有太平门.4.that引导同位语从句同位语从句是对前面名词的具体内容所作的详细阐述.例如：（1）We
are surprised at the fact that the children did it on their own
.听说孩子们独立做那件事,我们感到吃惊.（2）They expressed their hope that they would like to
go to visit the Great Wall
.他们表达了他们想去参观长城的愿望.二、that引导
定语从句that引导定语从句时,是
关系代词,它可指人（相当于who ,whom
）,也可指物（相当于which）.that在定语从句中可作主语,也可作宾语（作宾语时常可省略）.当定语从句修饰的
先行词既有人又有物时,只能用that引导定语从句.例如：1.This
is the museum (that / which) they visited last month
.这就是他们上个月参观的博物馆.2.They are going to the village that / which lies south
of the mountain .他们将去山南边的那个村庄.3.The man (that / who / whom) I shook
hands with just now is one of my old classmates
.刚才和我握手的人是我过去的一位同班同学.4.Do you still remember the things and persons that
we talked about at the meeting last month
你还记得上月我们在会上谈到的人和事吗?三、that用在
强调句型中强调句型的结构为：It is / was … that …
.如果被强调的是人,可用who代替that.如果被强调的是时间状语、地点状语或原因状语,则一般都用that.例如：1.It was on
July 30 that they decided to meet again .就是在六月三十日他们才决定再一次见面的.2.It is in
the classroom that we usually have our classes .我们通常是在教室里上课.
追问老师那个第二句的whice出现在句子中做什么意思呢
都是不作翻译的吗
追答This is the museum (that / which) they visited last month
你说的这句话吗？和that一样引导定语从句，也不翻译的。
追问是啊
老师为什么whice会出现在这个句子里呢