单项选择题
A.1B.5C.2D.3
A.45ºB.65ºC.75ºD.85º
A.BJ30T/18mB.BJ50T/29mC.JJ30T/18-WD.JJ80T/29-W
A.10mmB.12~15mmC.18~21mmD.22~25mm
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