I took a clear plastic tube and attached two circle protractors that could be rotated up and down the tube.
我找来一只透明的塑料试管，然后将两支可以旋转并上下移动的量角器接到试管上。
2
Lay out plate, sheet steel or other heavy metal and mark bending and cutting lines on work piece using protractors, compasses and drawing instruments or templates.
铺设莱板，钢板或其他重金属，用量角器，圆规和绘图工具或模板在工件上标记弯曲和切割线。
3
The double-sided protractor comprises two identical protractors and is structurally characterized in that a rotating shaft is arranged in the center ofthe two overlapped protractors.