-It’s very nice______ you to help me with my English．

-Not at all．I think it is important______ us to help each other

A．of, of                  B．for，of          C．of，for           D．for，for

It's very nice ___________ you to help me．

　　A．for　　B．of　　C．to　　D．with

It's very nice ________ you ________ help me.

[　　]

A. for；to help；of　　　　　　　　   B. of: to help; with

C. of；helping；for　　　　　　　　   D. for: helping; with