从经济内容看，下列属于流动负债账户的有( ) A．“应付债券” B．“预付账款” C

—Must I take a bus?

—No, you _______. You can walk there.  It's not far.     [ ]

A. must not        

B. don't

C. don't have to    

D. had better had to

液态烃碱洗反应是（）反应。

A、中和反应

B、分解反应

C、氧化反应

The whole book ________ 12 units, _________ two mainly revisions.

A．contains; containing

B．includes; contain

C．contains; including

D．includes; including

We should all remember that some great scientific discoveries _____________ by chance.

A．gained

B．discovered

C．occurred

D．earned

压缩机排气量不正常不可能的原因是（）。

A、空滤器阻塞

B、活塞磨损

C、发片密封不良

D、机油量过多