• 2021-04-14
    梯形钢屋架下弦杆常用截面形式是两个()。A.()不等边角钢短边相并,短边肢尖向下B.()不等边角钢短边相并,短边肢尖向上C.()不等边角钢长边相并,长边肢尖向下D.()等边角钢相并