单项选择 （共15小题；每小题2分, 满分30分）
1．the professor devoted all his life ____the treatment of aids．
a to research b．in researching c．to researchingd．at researching
2．they experimented _____the new medicine _____animals．
a．on; to b by ; on c．with ; on d with; to
3．you had better
