Question

Helen ________ her keys in the office so she had to wart until her husband ________ home．（NMET' 96．17）

1. A.
   has left；comes
2. B.
   left；had come
3. C.
   had left；came
4. D.
   had left；would come

Answer 1

C
第椄隹湛捎珊竺娴—had to来确定用过去完成时态，第二个空属从句，也由had to 确定用过去时。