Question

--- What did you think of Act I of the play last night?
--- I’m sorry. The play ________ when I got there

1. A.
   had been started
2. B.
   had been on for half an hour
3. C.
   was to start
4. D.
   had begun for half an hour

Answer 1

B
句意：戏剧在我到达之前就已上演了半小时，即表示“过去的过去”，且短暂性动词不与持续性时间连用，故须将 start→be on 才可与持续性时间连用。