肠外营养液中，能促进维生素C氧化分解、降低维生素B活性的成分是 （）
A.锌
B.铜
C.磷
D.钾
E.钙
参考答案：B
同生作用
—Dad, did you ride a bike to school when you_____a boy?
—No, my family was poor, so I usually _____to school on foot.[ ]
A. are; go
B. were; go
C. is; went
D. were; went
