肾脏的功能主要是（）

A.排泄

B.调节

C.内分泌

D.解毒

E.消化

—Mary, could you tell me if your mother ________ our school sports meeting tomorrow?　　

—I think she will come to school if she _________ free.　　

A．will take part in; will be

B．takes part in; is

C．will take part in; is

D．takes part in; will be