lesson 21 mad or not?
aeroplanes are slowly driving me mad. i live near an airport and passing planes can be heard night and day. the airport was built years ago, but for some reason it could not be used then. last year, however, it came into use. over a hundred people must have been driven away from their homes by the noise. i am one of the few people left. sometimes i think this house will be knocked down by a passing plane. i have been offered a large sum of money to go away, but i am determined to stay here. everybody says i must be mad and they are probably right.
must have done（主动）
must have been done（被动）
jack must have come back, for there's light in his house.
everybody says i must be mad and they are probably right.
must be doing（动作）
the case must be jack's, for there'a a label with his name on it.
jack must be looking for his case now.
jack can't be at home now, for i saw him in the street just now.
jack can't be playing basketball now, for it's raining heavily.
jack can't have found his case, for he's still looking for it now.