Helen always helps her mother even though going to school _____ most of her day. [ ]

A. takes up

B. makes up

C. saves up

D. puts up

孕妇需避免X线检查，是因为（）

A.X线的光化学效应

B.X线的荧光作用

C.X线的生物效应

D.X线的感光作用

E.以上都不是