When workers agree to forego leisure to undertake labor and receive wages, the term that is applied in labor supply economics is the:（）

A. substitution effect.

B. income effect.

C. marginal rate of substitution.

气相色谱法测定流体饱和度，是用定量的（）萃取油砂中的水进行色谱分析。

A.氯仿

B.乙醇

C.丙醇

D.甲苯