Question

We traveled overnight to Paris and arrived ________ 5 o’clock ________ the morning．

1. A.
   on; in
2. B.
   at; in
3. C.
   at; on
4. D.
   in; on

Answer 1

B
表示具体时刻、时间点用at表示；表示在上午用in; on用于表示某具体的日子或某一天的上午，如：on Sunday, on Sunday morning．