All flights ________called off because of the terrible weather, they had to go there by train.
| A．were | B．having been | C．being | D．had been |
28．Kids are often told to remain ______ they are and wait for their parents if they get lost．
| A．what | B．where | C．how | D．Who |
27．—What did you ______ while in college?
—English, politics and economics．
| A．take up | B．think up | C．bring up | D．make up |
26．I called Nancy many times but couldn't get through．Someone ______ on the phone all the time!
| A．has been talking | B．was talking |
| C．has talked | D．Talked |
25．How convenient the public transportation is! There ______ be any difficulty traveling around．
| A．mustn't | B．wouldn't | C．shouldn't | D．needn't |
24．—I just heard you had an adventure in the desert．
—We lost our way and ______ made matters worse was that our jeep broke down．
| A．how | B．that | C．it | D．What |