一位不知名的画家向著名画家门采尔诉苦说：“为什么我画一幅画只需要一天工夫，而卖掉

人的素质包括国民基础素质和各种专业或职业素质。国民基础素质主要包括_____、_____、_____等。专业或职业素质包括_____。

串级调节系统的方块图中，组成环节有（）

A、两个调节器

B、两个变送器

C、两个调节阀

D、两个被调对象

E、两个给定值

A certain grocery purchased x pounds of produce for p dollars per pound. If y pounds of the produce had to be discarded due to spoilage and the grocery sold the rest for s dollars per pound, which of the following represents the gross profit on the sale of the produce

A．(x-y)s-xp

B．(x-y)p-ys

C．(s-p)y-xp

D．xp-ys

E．(E) (x-y)(s-p)

I couldn't ______ the lecture at all. It was too difficult for me.

A．take on

B．take in

C．take over

D．take upon

自由电子运动方向与电流运动方向（）。

A、相同

B、相反

C、成角度运行

D、无关