21．—We often climb Xiang Shan. Hiking is _____ great fun.
—Yeah, when I get to _____ top of a mountain, I feel so satisfied.
A．a ; the B．/ ; a C．the ; / D．/ ; the
22．What kind of first aid should you perform in this situation ____ your nose is bleeding ?
A．which B．that C．who D．where
