trapezoidal shock pulse

例句：

1. 1. Theshape of the building is a trapezoid.
   这座建筑的形状是梯形。
2. 2. The areaof the square is equal to the areaof the trapezoid.
   正方形的面积等于梯形的面积。
3. 3. The trapezoidhas four sides and two vertices.
   梯形有四条边和两个顶点。