悠闲小猫
主语从句即用从句的形式作主语1.例that引导的:thattheearthisroundisture.你别看有两个动词is,就是错误的.这个句子也能缩写成:thatisround.(areyouunderstand)它是起连接作用,无实义.2.what引导的:whatwehavedoneisnouse.what是可以在主从中做成份（做主、宾、表）在该句引导主从在从句中做done的宾语.不可省,有实义.3.wether也能,不可省.但if不能.（是手机回答,字数有限）
霸气甫爷
语从句(SubjectClause)定义:如果一个句子在复合句中充当一个主语,那么这个句子就是主语从句.第一部分：常规主语从句，即句子在复合句中充当一个主语（1）Thathefinishedwritingthecompositioninsuchashorttimesurprisedusall.（2）Whetherwewillgoforanoutingtomorrowremainsunknown.（3）Whowillbeourmonitorhas'tbeendecidedyet.（4）Whomwemuststudyforisaquestionofgreatimportance.（5）Whatcausedtheaccidentremainsunknown.（6）Whateveryoudidisright.（7）Whosewatchwaslostisunknown.（8）Whatweneedistime.（9）Whatweneedaregooddoctors.小结:（1)引导主语从句连词有that,whether,who,what,whatever等（2)连词位于句首不能省略（3)主语从句大多数情况下视为单三,但也有例外,如例9第二部分：为了防止句子头重脚轻，通常把形式主语it放在主语位置，真正主语搁置于句末（1）Itiscertainthathewillwinthematch.（2）Itistruethathehasmadeaveryimportantdiscoveryinchemistry.（3）Itisverylikelythattheywillholdameeting.（4）Itisstrangethatheshoulddothat.（5）Itisimportantthatweallshouldattendthemeeting.（6）Itisstrangethatthemanshouldhavestucktohissillyideas.（7）Itisapitythatwewon'tbeabletogotothesouthtospendoursummervacation.（8）Itisstillamysterywhatcausedtheaccident.（9）Itissaidthathehasgonetoshanghai.(=Heissaidtohavegonetoshanghai)（10）ItisknowntoallthatthegunpowderwasfirstinventedbytheChinese.（11）Itissuggestedthattheworkshouldbedonewithgreatcare.（12）Itseemsthathehasseenthefilm.(=Heseemstohaveseenthefilm)（13）Ithappenedthatthetwocheatswerethere.(=Thetwocheatshappenedtobethere)小结:（1)以that引出的主语从句,常以形式主语it引导.Itis+形容词/名词/某些动词ed+that从句.（2)在有些that从句中要用虚拟语气(should+do/should+havedone)例句4,5,6,11.
人艰不拆XP
从句,就是用来描述句子成分特征的短句，分为前置和后置。主语从句一般只有后置，就是将从句放在主语的后面，加以修饰主语的特征，一般用who引导。例如：lilywhoisahighschoolstudenthasherowncompany.基本成分是lilyhasherowncompany。从句是who（lily）isahighschoolstudent
骆驼非洲
主语从句，即在复合句中充当主语成分的句子，例如"Thathefinishedwritingthecompositioninsuchashorttimesurprisedusall"，他在很短的时间内写完作文让我们都很惊讶，此复合句主要描述的是某事让我们惊讶，某事就是该复合句的主语，因此"Thathefinishedwritingthecompositioninsuchashorttime"便是该复合句的主语从句。引导主语从句的连词主要有:从属代词:thatwhether；连接代词:whowhoeverwhomwhosewhatwhateverwhichwhichever；连接副词:whenwherehowwhy；主语从句的时态：不受主句的时态影响和限制。（1）Thathefinishedwritingthecompositioninsuchashorttimesurprisedusall.（2）Whetherwewillgoforanoutingtomorrowremainsunknown.（3）Whowillbeourmonitorhasn'tbeendecidedyet.（4）Whomwemuststudyforisaquestionofgreatimportance.（5）Whatcausedtheaccidentremainsunknown.（6）Whateveryoudidisright.（7）Whothewatchbelongstoisunknown.（8）Whatweneedistime.（9）Whatweneedaregooddoctors.小结（1）引导主语从句连词有that,whether,who,what,whatever等。（2）连词位于句首不能省略。（3）主语从句大多数情况下视为第三人称单数，但也有例外，如例（9）。
