单选题 During the past two decades, research has _____our knowledge of daydreaming.

单选题 The advertisements______on the wall are designed by my sister.

单选题 If you ______ stop smoking, you can only expect to have a bad cough.

单选题 Hardly____back home when the telephone rang.

单选题 I ____ my keys. Can you help me look for them?

单选题 That proposal is essentially irrelevant ____ the issue at hand.

单选题 The new staff didn’t know how to use the system ______ I explained it to him yesterday.

单选题 ______ in the company for three years, Mark has become experienced in business negotiations.

单选题 The news about the terrible flood there greatly discouraged ______ there for sightseeing.