拖拉机件发生故障的车辆应注意什么？

More and more teaching _______ are being developed across the globe, which are sure to _______to    make classroom teaching more lively and interesting.      [ ]

A. aids; help      

B. assistance; help    

C. aids; assist    

D. helps; aid

Never in my wildest dreams _________ lead to a career in the NBA,which has allowed me to give back to my people in Africa.

A．I thought the chance would

B．I thought would the chance 

C．did I think the chance would

D．did I think would the chance 

木炭燃烧时，若有12g碳参加反应，则生成气体的质量不可能是[ ]

A．44g

B．28g

C．24g

D．33g

我国彩色电视制式采用的是______制。

A．NTSCM

B．PAL

C．SECAM

D．以上都不是

直涂的作用是消除圈涂、横涂的痕迹，使涂层更加平整、坚实、光滑。