單項(xiàng)選擇題信號(hào)集中監(jiān)測(cè)系統(tǒng)直流轉(zhuǎn)轍機(jī)監(jiān)測(cè)的單機(jī)動(dòng)作時(shí)間為()

A.0~20s
B.0~30s
C.0~40s
D.0~60s


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