下面哪条表达式可以创建一条从点（2,3）到（4,5）的线段？ A: Line(2,4,3,5) B: Line(2,3,4,5) C: Line((2,3),(4,5)) D: Line(Point(2,3),Point(4,5))

下面代码中，没有定义内部类或者错误定义了内部类的是（）。 A: public Class Line { int length; Class Point {//内部类代码}} B: public Class Line { public Point getPoint() { return new Point(){//内部类代码}; }} C: public Class Line { //外部类代码} Class Point {//内部类代码} D: public Class Line { public int calcLength() { Class Point {//内部类代码} }}

Thebreak even point is located at the intersection of the total revenue line andthe total expenses line on a cost volume profit graph.

《几何原本》中,（）是其第三条定义。 A: A line is breadthless length. B: A point is that which has no part. C: A straight line is a line which lies evenly with the points on itself. D: The ends of a line are points.

About the line graphs, we usually choose trend, change, ( ), bottom, beginning point, ( ), etc. A: percentage B: peak C: type D: ending point

Which of the following statements is wrong about curl? A: The curl of a vector field is a scalar and a function of the spatial coordinate points. B: At a certain point M in the field,[img=84x28]1803b721c59068a.png[/img] means that the vector line of this point is spinning. C: At a certain point M in the field,[img=84x26]1803b721cd97fe6.png[/img] means that the vector line of this point is spinless. D: Curl have the dimension of circumferential area density.

In the vector field, the vector line is such a curve where ( ) A: The tangent direction at each point on it is orthogonal to the direction of the vector field at that point. B: The tangent direction at each point on it is parallel to the direction of the vector field at that point. C: The value of each point on it is equal to the value of the vector field at that point. D: The vector line is the geometric curve of the vector field function.

If X and Y are measured in the same units and we consider a point that lies below a 45° line, then we know that for the X and Y combination associated with this point, <p></p>

ggplot绘制散点图的函数是（） A: point B: line C: geom_point D: geom_line

（）命令用于加载、建立及设置线型。 A: LINETYPE B: LINE C: LAYER D: POINT