The first use of atomic weapons was in 1945. and their power _____ increased enormously ever since.
| A．is | B．was | C．has been | D．had been |
Ladies and gentlemen, please fasten your seat belts．The plane ________．
| A．takes off | B．is taking off | C．has taken off | D．took off |
．He is always ready to help others, seldom, ______, refusing them when they turn to him．
| A．if never | B．if ever | C．if any | D．if not |
---Excuse me．Can you spare me a few minutes? ---______．
| A．What’s on? | B．What’s up? | C．What’s more? | D．What is it? |
Living in such a high mountain _________be cold．
| A．should | B．can | C．may | D．must |
－Is there any possibility ______ you could pick me up at the airport?
－No problem．
| A．when | B．that | C．whether | D．what |