测定中药中挥发油的组分和含量，常选用的仪器是( )
A．高效液相色谱仪
B．气质联用仪
C．气相色谱仪
D．薄层扫描仪
E．红外光谱仪
参考答案：C
— Thank you so much for saving my son and bringing him home.
— Don’t mention it. I only did what anyone else _______ in my place.
A．must do
B．should do
C．may have done
D．would have done
重要工程对粗骨料应进行碱活性的检验，理由是（）。
A．石子会被碱液腐蚀
B．防止碱骨料反应引起的破坏
C．防止引起抗冻性降低
D．检验石子中K2O和Na2O含量是否超标
