Teenagers must be careful not to let their part-time jobs______ too much of their time because study

is still their primary responsibility.[ ]

A. take on      

B. take away    

C. take up        

D. take after

在远程运输机上设置空中放油系统的主要目的在于：（）.

A.到达目的机场上空时放掉多于燃油，以便以较轻的重量着陆

B.起飞后发生紧急情况时放掉过多燃油，以便能够返场或到备降场着陆

C.飞行中放掉油量较多一边机翼油箱的燃油，以保持飞机横向平衡

D.以上都对