1.All flights ____ because of the storm ,they decided to go

1.All flights ____ because of the storm ,they decided to go to Beijing by train.
A having been canceled B had been canceled C having canceled D were canceled
2.We shall have completed the work by the time he ____ back next week .
A will come B comes C is coming D will have come
3.The little girl ___ into the lake but her father caught her.
A would have fallen B should have fallen C had probably fallen D has fallen
4.---“Do you often swim now ”
-----“No,but I ____ when I was in my fifties .”
A used to B am used to it C used to do D was used to doing
5.A new computer costs about _____ of this used one .
A the three times price B three time the price C three times a price D three times the price
综合各位的观点，我基本可以确定的答案是
1 A 2 B 4 A 5 D
现在有争议的是第三题，我个人觉得答案就在A,不过如果用would(not) have done的话，它应该常和if had done连用：
If you had told me earlier,I wouldn't have been so angry at that time.
如果你早点告诉我的话，我当时也不会那么生气呀。
should have done表示“本来应该做某事却没有做”，所以这句我觉得用should have done是合适的，
The little girl shoud have fallen but her father caught her.
（这个小女孩本来就要掉到湖里了，可是他爸爸接住了她。）
有人会说should have done?难道是咒这个孩子活该掉下去吗？”其实，should have done的“应该”并不是道义上的应该，而是理论上客观条件达到的一种结果，“本来就要...”
所以我现在决定的答案是
A B B A D
或者，哪位还有要补充的？
Much Confused!

1.A 因后面they decided...是一句子,前面all...没连词,所以不能是从句,只能是短语形式,所以只能A C,再排除C的主动形式,只有A
2.B 现在时表将来
3.A 虚拟语气,表与过去事实相反
4.A used to do sth 过去经常做某事（以前的习惯）,这里used是动词 过去时； be used to (doing) sth 对（做）某事很熟悉,这里used是过去分词
5.D 3倍用three times,price是特定的所以用the
【补充】 第3个 我认为 A,B都对,would的话可以表示一种推测,should可看做虚拟语气.这个题过于刁钻了,给老外做也未必搞得清楚,典型的中国考试题为难学生和老师的...