发布网友 发布时间:2023-07-12 00:37
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热心网友 时间:2024-12-02 16:12
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。 1.whether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/is I could help him. I want to know whether/if he lives there. 2.whether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。 1.whether可置于句首引导主语从句,而if不能。如: ___the 2000 Olympic Games will be in Beijing is not known yet. A.whether B.If C.Whether D.That 答案是C。 2.whether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 evough effort. 3.whether可引导表语从句,if则不能。如: The puestion is whether it is not worthdoing. 4.在名词之后引导同位语从句时,用whether而不用if。如: The puestion whether the students answered correctly should be decided by the teacher. 5.whether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.