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）ThatMrKinghadbeenputintoawomen”swardsurprisedhisboss.=ItsurprisedhisbossthatMrKinghadbeenputintothewomen”sward.金先生被安排在了女病房使他的老板很吃惊.（2）ThatProfessorWangwillgiveusalecturetomorrowafternoonisknowntoall.=ItisknowntoallthatProfessorWangwillgiveusalecturetomorrowafternoon.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：Itis/was+动词的过去分词+that从句.例如：（3）Itissaidthatthebookhasbeentranslatedintoseveralforeignlanguages.据说,那本书已被译成了几种外语.（4）Itisreportedthatasmanyas250,000peoplelosttheirhomesbecauseoftheearthquake.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）Hesuggested(that)weshouldkeepontrying.他建议我们继续努力.（2）Wemustbelieve(that)eachoneofusisabletodosomethingwell,andthat,whenwediscoveredwhatthisis,wemustworkhardatituntilwesucceed.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）Itseemsthatitismoredifficultforwomentogetjobsthanmen.似乎女人找工作比男人更难.（2）Thereasonwhysomanypeoplewerekilledinthebigfireisthatthebuildingwasbuiltwithoutanyfireescapes.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）Wearesurprisedatthefactthatthechildrendiditontheirown.听说孩子们独立做那件事,我们感到吃惊.（2）TheyexpressedtheirhopethattheywouldliketogotovisittheGreatWall.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.Thisisthemuseum(that/which)theyvisitedlastmonth.这就是他们上个月参观的博物馆.2.Theyaregoingtothevillagethat/whichliessouthofthemountain.他们将去山南边的那个村庄.3.Theman(that/who/whom)Ishookhandswithjustnowisoneofmyoldclassmates.刚才和我握手的人是我过去的一位同班同学.4.Doyoustillrememberthethingsandpersonsthatwetalkedaboutatthemeetinglastmonth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：Itis/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.ItwasonJuly30thattheydecidedtomeetagain.就是在六月三十日他们才决定再一次见面的.2.Itisintheclassroomthatweusuallyhaveourclasses.我们通常是在教室里上课.3.ItwasMsKingwho/thatpretendedtobeamaninordertogetajob.为找工作而女扮男装的是金女士.