高中英语名词性从句专题讲解及巩固练习定义：起名词性作用的从句，叫名词性从句。
本来该由名词充当的主语、宾语、表语和同位语部分，换由一个句子来充当，这样的句子就是名词性从句。
【归纳】1.只能用whether,不能用ifa.主语从句b. 表语从句c. 同位语从句e. 介词后的宾语从句f. whether to do 做动词宾语不能用if to do.g.whether or not 连在一起引导宾语从句时不用if.2.that和what的区别what除起连接作用外，还在名词性从句中充当成分，可做从句的主语、宾语、或表语。
that在名词性从句中不充当任何成分，只起连接作用。
例：I have no doubt that he will come.I have no idea what he did that afternoon.一．主语从句：在复合句中作主句的主语。
●__________ he is a famous singer is known to us.●__________ he will go to America is not yet fixed.●__________ she’s coming or not doesn’t matter too much.●__________ broke the glass yesterday is not clear.【keys】That; When/How; Whether; Who【归纳】1.为避免主语冗长,句子头重脚轻, 经常用it作形式主语, 主语从句放在后面作真正的主语。
例：That her hair was turning gray worried her a lot.-----It worried her a lot that her hair was turning gray.常考句型：It’s likely / possible / important / necessary / clear that…很可能/ 重要的是… / 必要的是… / 很清楚…It’s said / reported that…据说/据报道…It seems / appears / happens that…显然、明显、碰巧…It’s been announced / declared that…已经通知/宣布…It’s no wonder that…并不奇怪/无疑…It’s a pity/a fact /a common knowledge / a common saying that…2.if不能引导主语从句，只能用whether3.单个的主语从句作主语时，谓语动词用句单数形式；如果是两个或两个以上的主语作主语，谓语动词则视情况而定。
例：When and where he was born hasn’t been found.When he was born and where he was born haven’t been found.【巩固练习】1._________ makes this shop different is that it offers more personal services.2._________I can pay back the help that people give me makes me very happy.3.It’s not clear _________ was responsible for the accident.4._________ is in the regulations that you should not tell other people the passwordof your e-mail.5._________ he made an important speech at the meeting was true.6._________we’ll go camping tomorrow depends on the weather.7.________ is known to us all is that America is a developed country belonging tothe First World.8._________ worries my classmate Mary a lot these days is that she puts on toomuch weight and she is frequently ill.9. It makes no difference ________ you will go today or tomorrow.10.It is known to us ______ where there is pollution, there is harm.【keys】1.what 2.that 3.who 4.what 5.that6.whether7.what8.what9.whether 10.that二．表语从句：在复合句中作主句的表语。
新增引导词：as if, as though , because例：It looks as if it’s going to rain.【归纳】1. 如果句子的主语是suggestion, advice, order, demand, proposal等名词时,后面引导的表语从句用should+动词原形,should可省略。
例：His suggestion is that we (should) finish the work at once.2.固定句型：The reason why ...is that … … 的理由是，… 的原因是…It is because … 这是因为…【巩固练习】1.This town is _________ she was born.2.The question is _________ we can’t go there today.3.The reason why he has made such great progress is _________ he has never wastedhis time.4.My advice is that he _________ (go) to school by bike.5._________ she couldn’t understand was _________ fewer and fewer students showed interest in her lessons.6.Energy is _________ makes things work.7.The result is _________ we won the game.8.This is ________ we want to know.9. But where she could get suggestions and ________ will give her advice puzzles her.【keys】1.where 2.that 3.that 4.(should) go 5.what;why6.what7.that8.what9.who三宾语从句：在复合句中作主句的宾语。
【归纳】1.在谓语动词、介词、动词不定式、分词、动名词之后都可以带有宾语从句。
某些形容词如sure, happy, glad, certain, pleased 等之后也可以带有宾语从句。
例：We believe that he is honest.Pay attention to what the teacher said.I am sure/certain that he’s at home now.adj + 宾语从句，即“形宾”：形容词都是表示思想状况或感情色彩的形容词，如certain, sure, positive, afraid, convinced, anxious, disappointed, worried, glad, happy, sorry, amazed, surprised, aware, doubtful, confident等等2.如果宾语从句是由that 引导，and或but连接的两个或两个以上的并列的宾语从句, 那么只有第一个that可以省略，第二个或第二个以后的that不能省略.例：He said ( that ) the text was very difficult and that we had to work hard at it.如果宾语从句后还有宾语补足语，就用it作形式宾语，将宾语从句后置，并且that不可以省略.例：He has made it clear that he will win the game.3.表示“建议，命令，要求”的宾语从句，如advise, suggest, order, request, require, demand 等，从句用虚拟语气，即should+动词原形,should可省略。
4.在“主语+ believe/think/suppose/know/expect”的结构中，其否定形式要用否定转移，即主句否定，从句肯定。
例：I don’t think he will come.5.宾语从句的时态呼应：a. 如果主句时态是一般现在时或将来时,从句谓语可根据句意需要而选用任一种时态.b. 如果主句谓语是一般过去时,从句谓语动词一般用过去的某种时态,但如果从句表达的是客观事实、真理、自然规律等时，从句谓语通常用一般现在时。
【巩固练习】1.Tell me______ is on your mind.2.We must stick to ______ we have agreed on.3. To find out _________ she can get slimmer and healthier has become her main task4. Jane Goodall’s research makes_______ clear that chimps actually eat meat.5.Jane Goodall argues _________ wild animals should be left in the wild and not used for entertainment.6.No one knows exactly _________ the earth began, as it happened so long ago7.The girls began to realize ________ Canada is quite empty after two days’ travel.8.Burns are called first, second or third degree burns, depending on _________ layers of the skin are burned.【keys】1.what 2.what 3.how 4.it 5.that 6.when 7.that 8.which四．同位语从句在复合句中起同位语的作用。