主站与从站的通信方式为主从方式，即通信始终由主站发起，从站被动响应。主站按照事先规定好的次序周期性地依次访问其所属的各个从站，其数据传输是轮回分时进行的，称为（）。
A. 询问传输
B. 轮番传输
C. 轮回传输
D. 轮询传输
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那宝玉又听见他说“好姻缘”三个字，越发逆了己意，心里干噎，口里说不出来，便赌气向颈上摘下“通灵玉”来，咬咬牙，狠命往地下一摔，道：“什么劳什子！我砸了你，就完了事了!”偏生那玉坚硬非常，摔了一下，竟文风不动。宝玉见不破，便回身找东西来砸。黛玉见他如此，早已哭起来，说道：“何苦来，你砸那哑巴东西？有砸他的，不如来砸我！”《宝黛吵架》文中宝玉为何要砸“通灵玉”？
When fueling has been completed（）.
A. the fuel tank fill pipe should be left open to allow vapors to vent from the tank
B. the engine should be started immediately to prevent vapor lock in the fuel line
C. all hatches should be opened and all compartments should be ventilated
D. open the fuel line and drain a small amount of gasoline into the bilge to clear the line of sediment
An oxygen indicator will detect （）.
A. concentrations of explosive gas
B. an oxygen deficiency in a space
C. the presence of harmful amounts of carbon monoxide
D. All of the above
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