Question

“He was smoking.”

“Then he ________.”

1. A.
   ought to have been not smoking
2. B.
   ought to have not been smoking
3. C.
   ought not to have been smoking
4. D.
   ought to not have been smoking

Answer 1

C
ought to意为“应该”，相当于should，其否定式应在ought后加not。空缺处意为：“他本不应该这样一直抽烟”。