单项选择题
A.1mm B.2mm C.3mm D.4mm
A.1:15.5 B.1:16.5 C.1:15.6 D.1:16.6
A.34100J B.34200J C.34300J D.34400J
A.牵引粱 B.侧梁 C.枕梁 D.隔墙梁
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