Answer: Cong Cong is sitting in the second row and the fourth column of the classroom. There are several pairs (4, 2). Obviously, after Cong Cong, the obvious position is represented by several pairs (4, 3). So, B.
Analysis: From "Cong Cong is sitting in the second row of the fourth column in the classroom, represented by several pairs (4,2)", we can know that the first number in the pairs represents the column and the second number represents the row. Obviously, from the back of Cong Cong, he and Cong Cong are in the same column, and the number of rows is 1. According to this, the position where Mingcong sits can be represented by a number pair.
The key to solve this problem is to determine the meaning of each number in the number pair according to the known conditions. The columns before and after the moving point are unchanged, minus the number of rows and plus the number of cells moved; Move the same row left and right, and subtract the number of cells from the number of columns moved.
In mathematics, in order to analyze the algebraic relationship between points, lines and surfaces on a plane, the plane is divided into four parts with two vertical number axes, so that a point on the plane can be represented by a combination of a pair of values. The combination of these values is called the coordinates of the point. As shown in the figure, the coordinates of point A are (1, 1) and p (- 1, -2). The dotted lines (straight lines and curves) in a plane are all called graphs. A complex figure consists of many points and lines.
In the plane rectangular coordinate system, four areas divided by horizontal axis and vertical axis are divided into four quadrants. The quadrant takes the origin as the center and the X axis and Y axis as the dividing line. The upper right is called the first quadrant, the upper left is called the second quadrant, the lower left is called the third quadrant, and the lower right is called the fourth quadrant. The origin does not belong to any quadrant.