孔φ20+0.015 +0与轴φ20-0.010 -0.015配合,最大间隙是()。 ["0.030","0.010","0.015","0.025"]
半自动闭塞区间列车头部越过出站信号机的超长列车使用什么凭证发车?
简述泵轴承发热的原因及处理方法?
特种部队的营连队,如果无收文公章,可由()名章代替,但需向当地机要通信部门备案。 ["A、营、团长","B、政委、教导员","C、营、连长","D、教、指导员"]
下面平面度符号是()。 ["['['
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","
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"]
简述泵扬程不够的原因及处理方法。