1.You should try to get a good night's sllep____much work yo

1.You should try to get a good night's sllep____much work you have to do .
A.however B.no matter C.although D.whatever
我感觉应该D吧,可是答案上给的是A.
2.In England,a person with good manners____put several cakes on his plate at the same time.
A.would like to B.wants to C.is not supposed to D.prefers to
3.Orange represents ____.It can cheer you up when you are feeling sad.
A.wisdom B.ioy C.energy D.sadness
我知道选B,但是橘子为什么代表的是高兴呢?读音也看不出和高兴有什么联系啊
4.This engineer has made a contribution ____the computer software.
A.develop B.developing C.to developing D.to develop
这个我是一点都不会了,是不是有什么固定的句型?
5.If he___with us,we_____finish the task earlier.
A.were;will B.was;would C.is;will D.is;would
为什么选B不行呢?（答案给的是C）