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全部科目 > 水路交通运输技能考试 > 海船船员考试 > 船舶管理(轮机专业) > 轮机英语 > 船舶电气与船舶安全

单项选择题

In slow speed two-stroke engines,()the fresh air entering begins when and stops as()

    A.the inlet port is opened by the up coming piston; the port is closed by the down going
    B.the inlet valve is opened by the down going piston;the inlet valve is closed
    C.the inlet port is opened by the down going piston;the port is closed by the up coming
    D.the inlet valve is opened

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