21. It does not alter the fact that he was the man ________ for the death of the little girl.

　　A) accounting B) guilty C) responsible D) obliged

　　22. Medical care reform has become this country’s most important public health ________.

　　A) question B) stuff C) matter D) issue

　　23. Not that John doesn’t want to help you, ________ it’s beyond his power.

　　A) but that B) for that C) and that D) in that

　　24. I used to smoke ________ but I gave it up three years ago.

　　A) seriously B) heavily C) badly D) severely

　　25. The doctor told Penny that too much ________ to the sun is bad for the skin.

　　A) exposure B) extension C) exhibition D) expansion

　　答案： 21-25 CCABAa