名词性从句主语从句主语从句的语序主语从句要求使用陈述句语序，而非一般疑问句语序。如：Whatsurprisedmemostwasthatthelittlegirlcouldplaytheviolinsowell.使我感到惊讶的是这个小女孩的小提琴拉得太好了。Howhewassuccessfulisstillapuzzle.他是如何成功的仍然是个谜。连接词的选用（1）that和what的选用that和what都可引导主语从句。what除起连接作用外，还在名词性从句中充当某些成分，可作从句的主语、宾语或表语。而that在名词性从句中不充当任何成分，无词义，只起连接词作用。如：Whathewantsisabook.他想要的是一本书。Thatlighttravelsinstraightlinesisknowntoall.众所周知，光线沿直线运行。（2）if和whether的选用引导主语从句，不能用if，只能用whether。如：Whetherwewillholdapartyintheopenairtomorrowdependsontheweather.我们明天是否在户外开晚会要看天气而定。（3）其它连接代词和副词的选用根据主语从句的具体意义，正确的选择who,which,when,where,why,how等连接词，这些连接词既有疑问含义，又起连接作用，同时在从句中充当各种成分。如：Whenweshallholdoursportsmeetisnotdecided.我们何时举行运动会还没有决定。Whobroketheglassyesterdayisnotclear.还不清楚昨天谁打破了玻璃。Whichcaryouwillchoosetobuymakesnodifference.你决定买哪一辆车都不会有任何区别。（4）whatever/whoever的功用whatever,whoever在主语从句中不含疑问意义。它引导主语从句，并在从句中作主语、宾语、表语等。whatever=anythingthat;whoever=anyonewho。要注意和whatever,whoever引导的让步状语从句的区别。如：Whoeverbreaksthelawshouldbepunished.（主语从句）（＝Anyonewhobreaksthelawshouldbepunished.）Whoeverbreaksthelaw,heshouldbepunished.（让步状语从句）（＝Nomatterwhobreaksthelaw,heshouldbepunished.）it构成的主语从句（1）由连词that引导的主语从句，在大多数情况下会放到句子的后面，而用代词it作形式主语。谓语是seem,appear,becertain,beapity,beawonder,beone'shope,belikely等词或短语时。Itiswell-knownthattheearthmovesaroundthesun.众所周知，地球围绕太阳转。需要注意的是，it作形式主语代替主语从句时，要注意和as引导的定语从句的区别。试比较：ItwasreportedthattheUSwasundertheterroristattack.（主语从句，有that，无逗号）Aswasreported,theUSwasundertheterroristattack.（定语从句，无that，有逗号）上两句意为“据报道，美国遭到恐怖分子的袭击”。用于Itissuggested/required/ordered/demandedthat...句型中,动词为表示命令、建议、要求等意义的词。主语从句应使用虚拟语气,谓语动词用"should+动词原形",should可以省略。例如:Itissuggestedthatyou(should)spendmoretimeinstudyingEnglish.你应该花更多的时间学习英语。（2）常见用it作形式主语的复合句结构1.Itisafact（agoodidea/apity/ashame/nowonder/goodnews⋯）that⋯如：It'sapitythatyoumissedthefilm.你没有看那部电影真是太遗憾了。2.Itisnecessary（clear/true/strange/important/wonderful/possible/likely⋯）that⋯需要注意的是，这类主语从句中，谓语动词很多为“（should）＋动词原形”，即要用虚拟语气。如：Itisnecessarythatyou（should）masterthecomputer.你很有必要掌握电脑。ItisimportantthatastudentlearnEnglishwell.学生学好英语很重要。It'sclearthattheybadlyneedhelp.很明显，他们急需援助。Itislikelythatahurricanewillarrivesoon.飓风很可能马上就要到达了。3.Itisreported（well-known/hoped/thought/expected/said/believed/decided/suggested/ordered⋯）that⋯如：Itissaidthathewaskilledintheearthquake.据说他在地震中丧生了。4.Itseems（happened/appears/doesn'tmatter/makesnodifference/⋯）that⋯如：Itseemsthattheywillwinthegame.看起来他们好像会赢得这场比赛。Itmakesnodifferencewhetherhewillattendthemeetingornot.他是否会参加会议都无关紧要。TheForeignMinistersaid,"________ourhopethatthetwosideswillworktoward...
