单项选择题
A.30° B.60° C.90° D.120°
A.﹥10° B.﹥15° C.﹥20° D.﹥30°
A.0~100mm B.100~200mm C.200~300mm D.300~400mm
A.立即降下铲斗 B.立即熄火 C.跳车 D.立即反向行走
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