Question

英语单句改错

1.You ought to help him, but you did not. 2.The room is so quiet. They must have been asleep now. 3.We ought to not give up learning English halfway.

Answer 1

1. You ought to have helped him, but you did not.
ought to have done意思是：本应做但没做，而ought to do的意思是应该做（表示将来），从后半句来看，显然不能用ought to do
2. The room is so quiet. They must be asleep now.
must be是对目前发生的事的肯定猜测。而must have been是对过去事实的肯定推测。这个句子所陈述的事实是目前，所以不能用must have been
3. We ought not to give up learning English halfway.
ought to 的否定形式是 ought not to 或oughtn't to