必修3unit4grammar主语从句

1、 welcome! how dinosaurs disappeared is not only a question which interests biologists and geologists. it is a favorite topic for discussion for physicists and astronomers. they would like to know why dinosaurs became extinct because this may help them find ways to solve the problem of global warming

2、. some scientists believe that the earth slowly became hot and dry dozens of millions of years ago. how the climate changed is uncertain, but water and food supply decreased and so the dinosaurs gradually died out. however, the mammals survived. other scientists believe that comet crashed into the e

3、arth long ago and caused the disappearance. as a result of this event, a great dust cloud formed in the sky blocking out the sunlight. without sunlight, most plants soon died and so many dinosaur species became extinct. since the ice age, the climate of the earth has not changed very much. however,

4、whether the climate will change again is a concern for everybody on earth.1. 主语从句：从句在句中充当主语成分主语从句：从句在句中充当主语成分1) how dinosaurs disappeared is not only a question which interests biologists and geologists. only a question which interests biologists and geologists. how the climate changed is uncertain,

5、 but water and food supply decreased and so the dinosaurs gradually died out. 3)whether the climate will change again is concern for everybody on earth.1 引导主语从句的连接词有三类：引导主语从句的连接词有三类：(1) 连词连词that、 whether ：whether the climate will change again is a concern for everybody on earth.whether hell come her

6、e isnt clear. that price will go up is certain.what she did is not yet known.who will write the poem has not been decided yet.whatever he did is right.(2) 连接代词连接代词who, whom, whose, what, which, whoever, whatever, whichever等等3) 连接副词连接副词 where, when, how, why等。等。how this happened is not clear to anyon

7、e. when he will be back depends on the weather.how the pyramids were built is still a mystery. “it作形式主语：作形式主语： 为了避免主语冗长免主语冗长,句子头重脚轻句子头重脚轻,经常用经常用it作作形式主语形式主语,主语从句放在后面作真正的主语主语从句放在后面作真正的主语. 1.that we shall be late is certain.- its certain that we shall be late.2. that the earth is round is known to all

8、.- 3. that you missed the chance is a pity.- it is a pity that you missed the chance.its known to all that the earth is round. 4). that china has won 51 gold medals in the 29th olympics is reported. it is reported that china has won 51 gold medals in the 29th olympics.注注 意：意： what you left are only

9、several old books. what you said is of great importance.1.“if” 不能引导主语从句，应有不能引导主语从句，应有“whether”引导。引导。3.主语从句的主语从句的 “that” 一般不能省。一般不能省。4.“what”引导主语从句时，谓语动词：引导主语从句时，谓语动词： 1）常与其后的名词作表语一致）常与其后的名词作表语一致 2）根据句子的语）根据句子的语境而定。境而定。4. 主语从句需注意的问题主语从句需注意的问题2.主语从句中用陈述语序。主语从句中用陈述语序。it is doubtful if he has received y

10、our letter.1.where shall we spend the holiday isnt decided.2.you have made a mistake is a fact.3.that is certain that we can win.4.no matter who leaves the room last ought to turn off the lights.5.if the policemen will come is not certain.we shallthat you haveit iswhoeverwhether改错练习改错练习 _ he made an

11、 important speech at the meeting was true. a. that b. why c. what d. how 2. _well go camping tomorrow depends on the weather . a if b whether c that d where 3._ is known to us all is that america is a developed country_the first world. which; belong to b. as, belonged to a.c. what; belonging to d. it; belonging to4. its known to us all _ a form of energy . a. water is b. that water is c. is water d. that wa