第十讲名词性从句 名词性从句是历年高考的重点和难点，也是热点。名词性从句相当于名词，可作主句的主语、宾语、表语和同位语。因此，名词性从句可分为主语从句、表语从句、宾语从句和同位语从句(见下表)。名词性从句连接词主语从句用that,who,whether,if(不用于句首),what(＝thethingthat)等连接词引导宾语从句用that(可省略),if,whether(ornot),what(＝thethingwhich)等连接词引导表语从句用that(一般不省略),whether,what(＝thethingwhich)等连接词引导同位语从句用that(常指代news,thought,idea等词),whether等连接词引导结构常见句型Itis＋名词＋主语从句Itisafact/pitythat...事实是……/遗憾的是……/Itisanhonourthat...非常荣幸……/Itiscommonknowledgethat...……是常识/Itisaquestion＋疑问词...问题是……一、主语从句 主语从句是在复合句中充当主语的从句，通常放在主句谓语动词之前或由形式主语it代替，而本身放在句子末尾。1.用it作形式主语的结构结构常见句型Itis＋形容词＋主语从句Itisclearthat...……很清楚/Itissurprisingthat...令人惊讶的是……It＋不及物动词＋主语从句Itseemsthat...似乎……/Ithappensthat...碰巧……/Itappearsthat...看来……Itis/hasbeen＋过去分词＋主语从句Itisreported/said/believedthat...据报道/据说/人们认为……/Ithasbeenprovedthat...已证实……(续表)说明例句if引导的主语从句不可位于复合句句首Itsunknownwhether/ifhewillcome.(正)Whetherhewillcomeornotisunknown.(正)Ifhewillcomeornotisunknown.(误)Itissaid/reportedthat...结构中的主语从句不可提前ItissaidthatJackwillvisitourschoolnextweek.(正)Jackwillvisitourschoolnextweekissaid.(误)2.主语从句不可位于句首的五种情况说明例句Ithappensthat.../Itoccurstosb.that...结构中的主语从句不可提前Itoccurredtohimthathefailedintheexamination.(正)Thathefailedintheexaminationoccurredtohim.(误)Itdoesntmatterhow/whether...结构中的主语从句不可提前Itdoesntmatterwhetherheisrightornot.(正)Whetherheisrightornotdoesntmatter.(误)(续表)说明例句含主语从句的复合句是疑问句时，主语从句不可提前Isitlikelythatitwillrainintheevening?(正)Isthatitwillrainintheeveninglikely?(误)(续表)说明例句作动词的宾语由that引导的宾语从句(that通常可以省略)Myfatheralwayssays(that)nopains,nogains.我的父亲常常说，不劳无获。由what,whether/if,when,where,who等引导的宾语从句Hewenttoseewhowasoutside.他过去看是谁在外面。动词＋间接宾语＋宾语从句Sheexplainedtotheteacherwhyshewaslatethismorning.她向老师解释今早她为什么迟到。二、宾语从句宾语从句是在复合句中作宾语的名词性从句，通常放在主句谓语动词(及物动词)或介词