两道英语选择题,麻烦大家看看!Police are good people,but they can't do____A

两道英语选择题,麻烦大家看看!
Police are good people,but they can't do____
A,anything B,everything C,harm D,wrong
想选B,但不对,A和B有什么区别啊?
Members of the neighborhood watch group want to help the police______ their homes,streets,and families safe.
A keep B hold C let D protect
想选D,是保护的意思吧?,但答案是A,AD又有什么区别呢