I'm not sure if he is able to swim or not这句话是对的还是错的?急.坐等!

问题描述:

I'm not sure if he is able to swim or not这句话是对的还是错的?急.坐等!
刚考完英语,有一题I'm not sure______
A you can help me with my English.
B if he is able to swim or not
C how soon he will be back
D how long does it take to finish the job.
我选了B.不确定正确答案,加急!坐等!

I'm not sure if he is able to swim or not.是错的.
应该用whether代替if.
if 不能与or not连用,只有whether 才可以.
因为I'm not sure后面要加从句,所以A也是错的,应改成I'm not sure whether/if you can help me with my English.
从句中一般都是陈述句,D中does it take to finish the job是疑问句,所以不正确.
正确答案为C.我不确定他还有多久才回来.