He is very young.Iam not sure ____he can finish the work alone or not.A .how B .that C .whether D .i

题目

He is very young.Iam not sure ____he can finish the work alone or not.A .how B .that C .whether D .if
为什么不选D呀！短语有whether……or not,whether or not和if……or 有if……or not。whether或if均可表示“是否”的情况如下：引导宾语从句，例如
I wonder whether/if the news is true or not.

答案

选C whether表是否得意思
本句翻译为：他很年轻,所以我不确定他是否能够完成这项工作.
D项if是如果的意思,不能与or not连用,比如：
I don't know if he is at home or not.
I don't know whether he is at home.