在句子中起名词作用的句子叫名词性从句 (Noun Clauses)。 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,因此根据它在句中不同的语法功能,名词性从句又可分别称为主语从句、宾语从句、表语从句和同位语从句。
引导名词性从句的连接词可分为三类:连词(5个):that (宾语从句或表语从句中"that"有时可以省略)whether,if (均表示“是否”表明从句内容的不确定性)as if ,as though (均表示“好像”,“似乎”)以上在从句中均不充当任何成分连接代词(9个):what, whatever, who, whoever, whom, whomever, whose, which, whichever连接副词(7个):when, where, how, why, whenever, wherever, however不可省略的连词:1. 介词后的连词。2. 引导主语从句和同位语从句的连词不可省略。That she was chosen made us very happy.We heard the news that our team had won.比较whether与if 均为"是否"的意思。 但在下列情况下,只可用whether:1. whether引导主语从句并在句首。eg:whether he can come to the party on time depends on the traffic.2. 引导表语从句。eg:The question is whether we can get in touch with her.3. whether从句作介词宾语。eg:I am thinking about whether I should quit my present job.4.if与whether都可以与or not 连用,但后面紧跟or not 时只能用whether。we didn't know whether or not she was ready.(此时只能用whether)I wonder whether/if the news is true or not.(此时则二者都可以用)5. 引导主语从句。Whether he will come is not clear.大部分连接词引导的主语从句都可以置于句末,用 it充当形式主语。It is not important who will go.It is still unknown which team will win the match.
引导名词性从句的连接词可分为三类:连词(5个):that (宾语从句或表语从句中"that"有时可以省略)whether,if (均表示“是否”表明从句内容的不确定性)as if ,as though (均表示“好像”,“似乎”)以上在从句中均不充当任何成分连接代词(9个):what, whatever, who, whoever, whom, whomever, whose, which, whichever连接副词(7个):when, where, how, why, whenever, wherever, however不可省略的连词:1. 介词后的连词。2. 引导主语从句和同位语从句的连词不可省略。That she was chosen made us very happy.We heard the news that our team had won.比较whether与if 均为"是否"的意思。 但在下列情况下,只可用whether:1. whether引导主语从句并在句首。eg:whether he can come to the party on time depends on the traffic.2. 引导表语从句。eg:The question is whether we can get in touch with her.3. whether从句作介词宾语。eg:I am thinking about whether I should quit my present job.4.if与whether都可以与or not 连用,但后面紧跟or not 时只能用whether。we didn't know whether or not she was ready.(此时只能用whether)I wonder whether/if the news is true or not.(此时则二者都可以用)5. 引导主语从句。Whether he will come is not clear.大部分连接词引导的主语从句都可以置于句末,用 it充当形式主语。It is not important who will go.It is still unknown which team will win the match.