一氧化碳中毒时最先受累的器官是（）。
A．肺
B．脑
C．肾
D．肝
E．胃肠
参考答案：B
形成腰椎前凸的年龄
A.6～8周
B.3个月
C.6个月
D.1岁
E.1岁～1岁半
—Have you ever been anywhere for a trip?
—A trip? I _____ away from my hometown even once.[ ]
A. went
B. have gone
C. have never been
D. had gone
