所谓宾语从句，简言之就是该从句充当及物动词或介词的宾语成分。

eg: I don't know whether he will be able to come .我不知道他是否将能来。

he will be able to come 它在句子当中作know 的宾语成分 前面 I don't know 为主谓成分，如果把它看成简单句就相当于一个 主语+谓语+宾语 的结构 而whether 是连接词

1、 由that引导的宾语从句－当从句是陈述句时，用that引导宾语从句．在口语和非正式文体中，that可以省略 在宾语从句中很多时候that 是可以省略的

eg:

I know ( that ) you like English .

He told me ( that ) he would go there next week

2、 由whether / if 引导的宾语从句－当从句是一般疑问句，选择疑问句或反意疑问句时，用whether / if引导宾语从句,并且要把疑问的语序变为陈述的语序．一般情况下，whether / if可以替换．但下面四种情况，只能用whether引导宾语从句．

eg:

He asked me whether / if I liked my job .

I want to know whether / if you'll come to the party .

(A)当句子中出现 or not 时，必须用whether引导宾语从句

eg:

I want to know whether or not youlike me .

I want to know whether you like me or not .

(B)当主句的谓语动词是由”动词＋介词”构成的短语时，必须用whether引导宾语从句

They're talking about whether they'll go there.

(C)当宾语从句为了起强调作用，放在句首时，必须用whether引导宾语从句

Whether you like me , I want to know .

(D)当 if 容易引起歧义时，必须用whether引导宾语从句

Please let me know if you like it .

(宾语从句 ， if =”是否”）

Please let me know if you like it .

（条件状语从句, if = ”如果”）

3、关于疑问代词和疑问副词的我给你几个例句

eg:

We must know what to say at a meeting.

He could not tell whom to trust.

Do you know how to play bridge?

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