—Do you know the boy _______ is talking to Mr. Smith?—Yes, he's my brother.A. what B. which C. Who
David has a stomachache. _____ .
Mr. Brown is 70 this year. Although he is very old, ____ he works very hard.
–How often do you wash your hair?
Jim often goes to school _____ bike. But today he goes to school _____ the school bus.
I have _____ American friend. He is _______active boy.