A figure that can be folded over along a straight line so that the result is two equal halves which are then lying on top of one another with no overlap is said to have a line of symmetry. Which of the following figures has only one line of symmetry

A．Square

B．Circle

C．Equilateral triangle

D．Isosceles triangle

E．(E) Rectangle

承包人每填筑几层土后，应进行一次中桩、边桩恢复和纵断高程测量，以控制路堤的几何尺寸符合设计要求。