You'd better look up the new word in a dictionary(if)you don't know it?为什么不用whether?怎么翻译?

问题描述:

You'd better look up the new word in a dictionary(if)you don't know it?为什么不用whether?怎么翻译?

这里if是如果的意思,而不是是否,所以不能用whether
全句意思
如果你不明白那个词,你最好查字典~