几道英语时态,语态,虚拟语气,情态动词的高中题

1 Years ago,we did not know this,but recent science ___ that people who don't sleep well soon get ill.
A showed B has showed C will show D is showing
答案是B,为什么不是A?
看到横线后面的句子吗,是一般现在时.而且主语是recent science 近来的科学.
2.The year 2002 ___ remarkable changes in shanghai's landscape.
A sees B has seen C saw Dhad seen
答案是C,请解释并翻译一下.
主语是The year 2002 所以用过去式.
3.I would have finished the work more quickly,but I ____ that you were waiting.
A.hadn't known B.wouldn't known C.haven't known D.don't known
答案是A,Why?
意思是我本能够更快一些完成工作,但是我不知道你在等我.你在等用的是过去式,我不知道这个动作发生在你在等之前.
4.Because the shop ___ ,all the T-shirts are sold at half price.
A .has closed down B.closed down C is closing down D.had closed down
答案是C,为什么呢?
所有的T恤现在被以半价卖掉,所以这个商店快要倒闭了.
5.The dission _____ alive when an interesting topic was brought in.
A was coming B.had come C has come D.came
答案是D,问什么A 不对.
时间状语用的是过去式,所以前后时态一致.
6.Now that she is out of job,Lucky ___ going back to school,but she hasn't decided yet.
A .had considersd B.has been considering
C.considersd D.is going to considER
答案是B.C 哪错了?
最后半句说她还没决定,所以说她一直在考虑.现在完成进行时表示从过去的某一点发生,现在还在进行的动作.
7——What are you going to do this afternoon?
——I'm going to the cinema with som friends.The film ___ quite early,so we _____ to the bookstore after that.
A.finished ; are going B.finished; go
C.finishes; are going D.finishes; go
答案是C,第二空“so we are going to the bookstore” 我觉得应该是"so we are going to go to the bookstore".对不?
道理上对,但是和前面的重复了,为了避免重复,所以省掉了.依然表示将要去.
8.Under more favorable conditions,we _____ better.
A.could be done B.could have done C.should do D.needn't have done
答案是B,我选了C.
因为有more,所以用虚拟语气.如果没有more,用C可以.