18. A) To protect her from getting scratches.
B) To help relieve her of the pain.
C) To prevent mosquito bites.
D) To avoid getting sunburnt.
W: These mosquito bites are killing me. I can’t help scratching.
M: Next time you go camping, take some precaution, say wearing long sleeves.
Q: Why does the man suggest the woman wear long sleeves?
［答案］C)。[听前猜测]四个选项都是不定式作目的状语，听音时要注意说话人做事的目的。[精解]对话中女士埋怨蚊子咬得她忍不住直挠，男士建议她下次野营时要采取防护措施——穿长袖衣服。可见男士建议女士穿长袖衣服是为了预防蚊子叮咬。故本题答案为C)。