【单选题】Falls Company has budgeted sales of $120,000 based on 80,000 units. The margin of safety is $1,000. What is the break-even point in dollars?
【简答题】电流所做的功,简称 ,用字母 表示,单位是 ;电流在单位时间内所做的功,称为 ,用字母 表示,单位是 。
【简答题】已知大圆的半径为R,小圆的半径为r,圆环面积为S. (1)用代数式表示圆环的面积S; (2)当R=5,r=3时,求S(结果保留一位小数).
【单选题】After doing some shopping, they went to open the door of ______ car.
【单选题】—After P.E., I often feel very thirsty. —Why not buy some ________ to drink?
【简答题】已知大圆的半径为R,小圆的半径为r,圆环面积为S. (1)用代数式表示圆环的面积S; (2)当R=5,r=3时,求S(结果保留一位小数).
【判断题】电荷的有规则运动称为电流。电流强度是以单位时间内通过导体截面的电荷量来表示,习惯上简称为电流。( )