作业帮He didn't know if he had passed the exam.这句话从语法上来讲对吗?didn't know 能与 if 句末需要加or He didn't know if he had passed the exam or not.
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He didn't know if he had passed the exam.这句话从语法上来讲对吗?didn't know 能与 if 句末需要加or He didn't know if he had passed the exam or not.
He didn't know if he had passed the exam.这句话从语法上来讲对吗?didn't know 能与 if
句末需要加or He didn't know if he had passed the exam or not.
He didn't know if he had passed the exam.这句话从语法上来讲对吗?didn't know 能与 if 句末需要加or He didn't know if he had passed the exam or not.
if 与whether 的用法：1.if作“是否”意思的时候,与whether同义,都可引导宾语从句,可以互换.
2.口语中常用if,但是从句中有or not的时候,则只能是用whether,例如：I don‘t know whether it’s snowing or not.
3.whether可以引导主语从句,表与语句,同位语从句,if 则不能,if意为“如果”可以引导条件状语从句,whether则不能,whether可以和不定式连用,if 则不能.4.whether引导的宾语从句可以放在介词后面,if引导的宾语从句则不能
语法上是对的。及物动词know 后面接的if 从句是宾语从句，这个时候if=whether ,是否的意思
语法是不对的。
如果要表示他不知道这个事实，则为 he didn't know that he had passed the exam.
如果表示他不知道是否通过，则为he didn't know if he had passed the exam or not.
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可以。相当于whether，引导宾语从句
这里的if不是假如的意思，而是是否，可用whether代替，所以语法上并没有错误
对的，if引导的是宾语从句，“是否”的意思。如果不用否定，那此句应该是这样的：He knew that he had passed the exam.
把if换成whether，就可以加or not了。