Question

________ entered the classroom _________ the bell rang.

1. A.
   We hardly had, before
2. B.
   Hardly had we, when
3. C.
   Hardly had we, than
4. D.
   Hardly did we, when

Answer 1

B
hardly…when… “一…就…”。Hardly开头句子采用部分倒装而且后面的句子时态用过去完成时，when后的句子不倒装而且用一般过去时态。所以选B。