— I promise to go shopping with you if you help me with the housework.

— _____.You are the last person to keep a promise. [ ]

A. That's great

B. Come off it

C. I don't agree

D. I don't believe so

六氟化硫介质具有优越的（）性能。

A.绝缘；

B.耐腐蚀；

C.防潮；

D.灭弧。