以硅胶为固定相的薄层色谱通常属于
A．分配色谱
B．吸附色谱
C．离子抑制色谱
D．离子交换色谱
E．离子对色谱
参考答案：B
Recently I bought an ancient Chinese vase, _____was very reasonable. [ ]
A. which price
B. whose price
C. the price of that
D. its price
在自控系统中一般微分时间用（）表示。
A、P
B、I
C、D
D、PI
