21. ---Do you mind my smoking here?

---_________.

A. No, thanks.       B. No. Good idea.     C. Yes, please.    D. Yes. Better not.

22. Never travel with ___________ who leaves you in case of danger.

A. the friend        B. that friend         C. a friend            D. friend

23. The explorers were told to __________ themselves with everything they would need for the voyage.

A. associate        B. equip            C. relate           D. feed