单项选择题
A.2~3 B.3~4 C.4~5 D.5~6
A.水平杆 B.斜杆 C.立杆 D.脚手板
A.120mm B.130mm C.140mm D.150mm
A.1/2 B.1/3 C.1/4 D.1/5
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