二．单项选择：（共15个小题，每小题1分，满分15分）
21. ---Waiter?
---______
--- I can’t eat this. It’s too salty.
A. Yes, sir? B. What? C. All right? D. Pardon?
22. It ____ have been Tom that parked the car here, as he is the only one with a car.
A. can B. must C. might D. will
23. Dear sir, it is so generous _____ you to share your room and food ___ me.
A. of; with B. for; with C. of; to D. for, to
