She calls back whenever someone ______ her a message.
..---You haven't said one word about the design, Joe. What's your idea? ---Sorry. I________about something else.
---Have you found your book yet? --- No, I’m not sure where I________it?
I want to buy that kind of cloth because I ________the cloth________well.
________it________to rain tomorrow , the sports meet would be put off until the same time next week.
Going on a trip________be expensive and difficult , so making a plan is necessary. A. must B. ought to C. shall D can