单选什么的最讨厌了！！！！！！！！！！！！！~

Mr.smith often stays up,_______lessons,books spread all over the desk.
A preparing B prepared C to prepare D prepares
我知道选A。
但我们老师说什么如果B+个FOR就可以用了。
难道其他的不用+？？
还有一道- -
The news came as no surprise to me . i ___ for some time that the factory was goning to shut down.
A have known B had known C kne D was knowing.
为虾米选B不选A。