He is very young.Iam not sure ____he can finish the work alone or not. A . how B .that C .whether D .if
解释一下呀 !为什么不选D呀! 短语有whether……or not,whether or not和if……or not啊!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.