题目

根据短文内容从A、B、C、D四个选项中选出一个能填入相应空格内的最佳答案。How do you imagine thefuture? Will life in the future be better, worse or the same as now?1doyou think of the future?People 2 that life will probably be very different in2050. First of all, larger planes 3, so flying will be very cheap. Solarpower(太阳能) will be used in the carsand the cars will be much cleaner and safer. Everyone will have such a car.Robots will be 4 here and there. And space planes will take usaround the world 5 two hours. Homes will be warm in winter andcool in summer, .（2010·湖南祁阳四中高三上第一次月考）      31. ─ Professor Brown, I enjoyed your lecture at HK University last year. ─Thanks. But it ______ over two years ago, if I can remember rightly. A. must have been    B. can be          C. may be          D. might be