Each person who receives____Nobel Prize is given a cash priz

Each person who receives____Nobel Prize is given a cash prize,a gold medal and____special paper which explains the prize the person won.
A.a the B.the a C.a a D.the the
一道完形填空题：
The officers____down the door and cleaned the house.
A.pushed B.knocked C.struck D.hit
这题是指一道锁着的门,警察撞了进去.请帮忙区别一下struck hit和knocked的区别.