If you are hunting         chance to improve yourself in English, I think the English corner will be        ________smart choice.

A．a; a

B．a; the

C．the; a

D．the; the

原位癌是指

A．早期癌

B．原发癌

C．癌前病变

D．未发生转移的癌

E．未突破基底膜的癌