煤矿井下电缆主芯线的截面应满足供电线路过负荷的要求。

— Why do you do volunteer work in the North-West?

— I___ to improve the lives of the children there through my efforts．

A．was trying

B．have tried

C．am trying

D．tried

黏性大的原料（ ）含量大。

A．支链淀粉

B．直链淀粉

C．糖淀粉

D．糖胶

昂科威的后备箱容积达到了（）L，放倒座椅后达到（）L，超越同级车型。

A.422；1550

B.420；1550

C.422；1450

D.420；1450