Question

It’s necessary ______ us to keep our pets clean everyday.

A．of

B．for

C．with

D．between

Answer 1

B

“It is + adj.+ of sb.+ to do sth”句型中的adj.跟sb.有关,这个adj.是用来形容sb.的,表示某人这么做真是太adj.了。如：It’s very kind of you to help me.而“It is + adj.+ for sb.+ to do sth”表示做某事对某人来说很adj.，这里的adj.是do sth的属性，里面的sb.跟adj.没有直接联系。故根据句意选B。