第三节 语法和词汇知识（共15小题；每小题1分，满分15分）
从每小题的A、B、C、D四个选项中，选出可以填入空白处的最佳选项，并在答题卡上将该选项涂黑。
11. Do you doubt _______ he will win?
A. whether B. if C. that D. when
12. The room _______ very useful when we had visitors.
A. was proved B. has been proved C. has proved D. proved
13. I can’t leave the office now. A lot of work ________ to be done.
A. is remained B. left C. remains D. have
14. The villagers went out to the mountain __________ the missing child.
