Faced with_______ failure, it is the most important for us to keep up ______good state of mind.

A． / ; a

B． a ; /

C． the ; /

D．/ ; the

If you don’t know the answer to something, you say: “______”

A．Sorry, I don’t understand.

B．I’m sorry. I don’t know.

C．Can I speak English?

D．Excuse me. How do you say that in English?