轨道是列车运行的基础，它直接承受列车载荷，并引导列车运行。
参考答案：对
I was ________ at this news that the hospital had burnt down. [ ]
A. astonished
B. delighted
C. interested
D. excited
高渗状态有哪两类（）
A.高钠血症和高钾血症
B.高钠血症和高钙血症
C.高钠血症和高糖血症
D.高钾血症和高糖血症
E.高钙血症和高糖血症
