在句子中起名词作用的句子叫名词性从句。名词性从句的功能相当于名词词组,它在复合句中能担任主语、宾语、表语、同位语、介词宾语等, 因此可分别称为主语从句、宾语从句、表语从句和同位语从句。主要考查语序问题、连接词选用、时态的 呼应等
who will win the match is still unknown.
i want to know what he has told you.
the fact is that we have lost the game.
the news that we won the game is exciting.
从属连词： that, whether, if 不充当从句的任何成分
连接代词: what, whatever, who, whoever, whom, whose, which, whichever. （作主、宾、表、补）
when, where, how, why, however, wherever（状）
1．that the earth is round is true.
= it is true that the earth is round
2. whether he will come hasn’t been decided.
= it hasn’t been decided whether he will come.
注意: 连词that, whether在从句中不担任 句子成分,只起连接作用,不能省略 (注: if不可用来引导主语从句）
when he will go to america is not yet fixed.
(it is not yet fixed when he will go to america.)
whoever leaves the room last should close the door.
whatever we do must be in the interests of the people.
1）it is a fact that he won the match.
2）it is necessary that we do study the english.
3）it is known to all that light travels in straight lines.
4）it seemed that he would come here
it is + 名词 + that从句 it is a fact/a shame/a pity/no wonder/
it is + 形容词 + that从句 it is necessary/strange/important/
it is + 过去分词 + that从句 it is said/reported/decided/known/
it + 不及物动词 + that从句 it seemed/happened/doesn’t
matter/has turned out/…that
it 作形式主语代替主语从句,主要是为了平衡句子结构, 主语从句的连接词有变化。而it引导的强调句则是对句子某一部分进行强调,无论强调的是什么成分,都可用连词that。被强调部分指人是也可用who/whom。例如:
it is a pity that you didn’t go to see the film.
it doesn’t interest me whether you succeed or not.