动车段（所）宜设置进站信号机、进路信号机、调车信号机。
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用户进程对信号的响应可以有3种方式：（）、捕捉信号、（）
轧钢加热炉常用的蓄热式烧嘴有（）和空气煤气双预热两大类。
小型空分设备改用分子筛纯化器净化空气时，应注意哪些问题？
Which of the following statements is TRUE regarding automatic identification systems (AIS)? （）
AIS is a short-range VHF-FM system that automatically broadcasts a vessel's position，course，speed and other safety related information to all those with similar equipment in the area
B. AIS is a one-way centrally managed system that requires the local VTS to send commands to instruct each vessel to broadcast position，course，speed and other safety related information to all those with similar equipment in the area
C. AIS is a global tracking system that relies upon INMARSAT C service to communicate vessel position，course，speed and other safety related information to all those with similar equipment in the area
D. AIS is a short-range 3 cm X-band radar system that automatically sends a vessel's position，course，speed and other safety related information to all those with similar equipment within the area
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