坚持党的基本路线，关键是坚持以经济建设为中心。( )
参考答案：对
解析： 以经济建设为中心是党的基本路线的核心内容。
— What happened to your brother?
— He slipped on the icy road _____ after a bus, and had his leg broken. [ ]
A. to chase
B. chasing
C. chased
D. having chased
维生素D的两次羟化是在
A．骨和肾
B．肺和骨
C．肝和肠
D．肝和肾
E．肝和骨
