whether和if的用法区别
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w h e t h e r和i f的用法
区别
Company Document number:WTUT-WT88Y-W8BBGB-BWYTT-19998
whether和if的用法区别
whether与if作“是否”讲,在用法上有相同之处,也有不同之处.
一、相同之处.
和if都能引导宾语从句,常置于
see,ask,learn,tell,wonder,doubt,find out等动词之后.
如:He asked me whether/if I could help him.
I want to know whether/if he lives there.
和if都可用it作形式主语从句中.
如:it's uncertain whether/if he'll come this evening. 3.在be uncertain/doubtful之后,常用whether引导宾语从句,有时也可以用if.
如:We are uncertain whether/if Mary will come.
二、不同之处.
可置于句首引导主语从句,而if不能.
如:___t
可用在介词之后,引导宾语从句,而If则不能.
如:Success depends on whether we make enough effort.
可引导表语从句,if则不能.
如:The question is whether it is not worth doing.
4.在名词之后引导同位语从句时,用whether而不用if.
如:The question whether the students answered correctly should be decided by the teacher.
后可接不定式,而if不能.
如:Please tell us whether to go or stay here.
6.在有些动词(如discuss)之后,只能用whether,而不用if引导宾语从句.
如:We discussed whether we should close the shop.
7.在引导否定概念in宾语从句时,只能用if,而不用whether. 如:he asked me if I hadn't finished my work.