Question

whether和if在表语从句中的区别

Answer 1

whether, if引导从句的用法区别:
①引导主语从句.表语从句或同位语从句时.用whether.不用if.
例如:Whether they will go to the Great Wall is not known./ The question is whether we can finish the task on time./ The question whether we will take part in the physics contest has not been decided.

②whether可接不定式.而if则不可.
例如:I haven’t decided whether to leave or not.

③whether可作介词的宾语或置于句首表示强调.而if则不可.
例如:Everything depends on whether we have enough money./ Whether he will come, I am not sure.

④whether和if均可引导宾语从句. whether引导的宾语从句一般都是肯定句.if引导的宾语从句可以是肯定的.也可以是否定的.
例如:Could you tell us whether/ if it rains in winter in Australia?/ I wonder if it doesn’t rain.

⑤引导宾语从句的whether和if常可与or not连用.连用时要注意or not的位置.它一般与 whether.if分开使用.有时它可与whether合起来使用.但不能与if合起来使用.
例如:I don’t know whether/ if they will come or not./ I don’t know whether or not they will come.

⑥if可用来引导条件状语从句.译“如果 .whether则不行.
例如:If you work hard, you are sure to succeed.

Answer 2

引导表语从句时不用if。如：
The question is whether we can get there on time. 问题是我们能否按时到达那里。