气相色谱法中常用的载气是（）
A.氧气
B.氢气
C.空气
D.氮气
E.惰性气体
参考答案：D
The crowd cheered wildly at the sight of Liu Xiang, who was reported the world record in the
110-metre hurdle race.[ ]
A. breaking
B. having broken
C. to have broken
D. break
最小的两位数是[ ]
A．10
B．11
C．12
