用括号内所给单词的适当形式填空。（5分）
1. He shows great interest in _________ (chat) with his classmates by QQ.
2. I prefer _________ (music) who play many different kinds of songs.
3. If I had a million dollars, I’d give it to _________ (medicine) research.
4. John _________ (drop) his wallet on the ground while walking on the road.
5. Please speak ___________ (clear), or others can’t catch what you mean.
