Question

not sure后从句用can还是could

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!

Answer 1

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.