Ⅴ. 单项选择（每小题1分， 共15分）
( )21. Mike, do you know the answer ________ Question 4? It’s a little difficult for me.
A. with B. To
C. for D. at
( )22. My cousin decided to leave tonight, ________ I asked him not to.
A. because B. if
C. when D. although
( )23. —I’d like some more cakes, Mom.
—I’m sorry, Jane. There’s ________ left.
A. few B. some
C. none D. many
( )24. The ________ took out the boy’s bad tooth and told him not to eat too many sweets in the hospita