1、英语选修8(人教版)第四学时 Grammar 语 法 精 讲一、引导名词性从句的引导词可分为三类 语 法 精 讲1连接词。(1)引导词that本身无词义，引导陈述句语气在从句中不充当成分。That_he_passed_the_examination made his mother very happy.(2)引导词whether/if/as if有词义，但在从句中不充当成分，如whether，if和as if。It seems as_if_he_were_not_interested_in_this_project 语 法 精 讲2连接代词。引导词本身有词义且在句中充当成分，如who，whom
2、，whose，what，which。I dont know who/whom_I_should_believe3连接副词。引导词本身有词义且在句中充当成分，如when，where，why，how。We havent decided when_well_go_to_Tibet二、主语从句、表语从句和宾语从句 语 法 精 讲1.主语从句在整个句子中作主语，包含两类，形式主语和真正主语。(1)that引导主语从句时不能省略。That_the_driver_could_not_control_his_car was obvious.(真正主语)It was obvious that_the_drive
3、r_could_not_control_his_car(形式主语)语 法 精 讲(2)if不能用在句首引导主语从句，这时用whether；与or not 搭配表“是否”时，也只能用whether。Whether_he_left_(or_not)is unknown.(3)当主语是一个从句时，谓语动词一般用第三人称单数。What_we_need is more time and money.语 法 精 讲2表语从句出现在系动词后。The trouble is that_we_are_short_of_moneyGo and get your coat.Its where_you_left_it(
4、1)引导表语从句除了上述三类词外还有because，as if/as though等。请注意下列句型：The reason(why/for which.)is that.The reason why he was absent was that he was ill.The reason why he failed in the exam is that he was so lazy and careless.语 法 精 讲It/This/That is because.It is because_you_dont_know_how_much_I_love_you(2)连系动词appear，l
5、ook，seem的两个常用句型：It seems/appears that.It looks/seems as if/as though.(与事实相符用陈述语气，与事实相反用虚拟语气)It seems as_though_he_knew_nothing_about_the_truth(3)as 也可以引导表语从句。Things are not always as_they_seem_to_be 语 法 精 讲3宾语从句作及物动词、be形容词和介词的宾语。(1)宾语从句的时态与主句相呼应，但宾语从句表示的是客观真理或普遍现象时，从句谓语常用一般现在时。The teacher told us th
6、at_the_earth_moves_around_the_sunIm afraid that_it_will_rain_tomorrow(宾语从句)He is interested in_what_his_teacher_said(介词宾语从句)语 法 精 讲They doubt whether it_is_useful(及物动词宾语从句)(2)连词whether和 if可以互换，但要注意下列情况：连词后紧跟or not时用whether。I want to know whether_or_not_they_will_come从句作介词宾语时用whether引导。He was interes
7、ted in whether_he_saw_her_there连接词后直接加不定式，不能用if只能用whether。He doesnt know whether_to_stay_or_not 语 法 精 讲位于句首疑问语气的主语从句引导词，只能用whether.Whether he will succeed depends on his attitude.位于句首疑问语气的主语从句引导词，只能用whether.Whether he will succeed depends on his attitude.如果宾语从句是否定时，一般用if引导。I care if_he_will_not_atte
8、nd_the_meeting(3)当宾语从句后带宾补时，要用句型“主语谓语it 宾补that从句”。语 法 精 讲I think it certain that_she_will_do_well_in_her_exam(4)当主语是I，we，动词 think，believe，suppose，expect，imagine后带否定意义的宾语从句时，要将否定转移到主句。I dont_think he will win the game，will he?语 法 精 讲4注意区分it 作形式主语的主语从句与强调句的区别。强调句句型“It is/was被强调部分that”，去掉“It is/was.tha
9、t”，句子仍然成立。It is natural that_they_should_have_different_views(主语从句)It_is only lately that he has had a family himself.(强调句)It_was in the hotel where he stayed that we discussed the serious problem.(强调句)语 法 精 讲5注意it 作形式主语的主语从句和as引导的非限制性定语从句的不同。It is known to all that_the_earth_is_round(主语从句)As_is_known_to_all，the earth is round.(非限制性定语从句)
