要素禀赋理论的提出者是（）。
A.亚当·斯密
B.大卫·李嘉图
C.里昂惕夫
D.赫克歇尔
参考答案：D
离心式主油泵入口油压必须大于大气压力。
What happened 25 years ago（）
A. Michael’s parents got divorced.
B. Karen’s mother died in a car accident.
C. A truck driver lost his wife in a collision.
D. Karen was adopted by Ray Anderson.
