单项选择题
A.100mm B.120mm C.80mm D.60mm
A.C15 B.C20 C.C30 D.C10
A.Ⅰ级钢筋 B.Ⅱ、Ⅲ级钢筋 C.钢丝束 D.钢绞线
A.30°～45° B.45°～60° C.20°～30° D.5°～20°
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