1. It is really cold and the ground is wet； it have rained last night．（ ）
A. might B. must C. can D. should
2. What is the best way you can imagine ______ the overuse of water in our daily life．（ ）
A. to reduce B. reducing C. reduced D. reduce
3. _________it many times， I still can't make Tom understand what I said．（ ）
A. Explained B. Having explained
C. To explain D. Having been explained
4. No one______be more warm-hearted； he has a heart of gold.（ ）
A. should B. can C. might D. need
5. One of the meteor （陨石） pieces was found to have crashed into a frozen lake， ______ a six-meter wide hole．（ ）
A. left B. leaving
C. to leave D. having left
