Choose the best choice:
1. _____ is still unknown.
A. How did he solve the problem B. How he solved the problem
C. Whether did he solve the problem or not D. What did he solve the problem
2. The old lady picked out the person in the crowd _____ she was sure had robbed her of her necklace the week before.
A. whom B. who C. what D. /
3. The young couple were anxious and they begged the doctor to do _____ he could to save their daughter’s life.
A. that B. what C. all what D. which
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