In my point of view, the question is not _____ the world is going to have a new economic crisis, but when.
30.It's a good habit to have your car brakes ______ before a long journey.
29.—The cleaning must have taken you quite a long time yesterday. —Right.The rooms ______ for two months.
28.Kids are often told to remain ______ they are and wait for their parents if they get lost.
27.—What did you ______ while in college? —English, politics and economics.
26.I called Nancy many times but couldn't get through.Someone ______ on the phone all the time!