为了供儿子读完大学，我们生活非常拮据。We lived on the breadline to get our son through college.消费者支出在减少，商人感觉手头拮据。Consumers are spending less and traders are feeling the pinch.她的父母手头很拮据。Her parents were very hard up....
This obviously derails the forward - momentum process.很明显这是前进途中的一大障碍.Longitudinally polarized electrons are the electrons with spin and momentum pointing in the same direction.纵向极化电子,就是自旋和动量方向相同的电子.In the case of populat...