气相色谱图的横坐标是（）。
A、时间
B、体积
C、质量
D、浓度
E、温度
参考答案：A
I _________ know.[ ]
A. am not
B. doesn't
C. don't
D. aren't
We thought Tom wouldn't pass the exam, but to ___, he passed.
A．the surprise
B．my surprised
C．our surprise
D．our surprising
