2. A 本题考查句型have difficulty (trouble, problem, a difficult / hard time) (in) doing sth.

3. C本题考查freeze的被动语态，句意为：整条河都被冻住了。而freezing可以形容天气，如：It’s freezing today.

4. D
5. A
6. B
7. C
8. D
9. A
10. C
11. D
12. A
13. C
14. B
15. C