【单选题】Scientists say it may be five or ten years _____ it is possible to test this medicine on human patients.
【单选题】During operation of L/C, ( ) guarantees to buy all the documents from the exporter.
【单选题】During operation of the engine, the fuel supply draws fuel from the , forces it through the filter to the injector pump.
【多选题】根据《低压配电设计规范》,以下说法正确的是()
A.
在三相四线制配电系统中,中性线(以下简称N线)的允许载流量不应小于线路中最大不平衡负荷电流,且应计入谐波电流的影响
B.
以气体放电灯为主要负荷的回路中,中性线截面不应小于相线截面
C.
采用单芯导线作保护中性线(以下简称PEN线)干线,当截面为铜材时,不应小于10mm 2
D.
直接敷设在土壤中的电缆应采用敷设处历年最热月的月平均温度值
【单选题】0“不经一事,不长一智”,这句俗语蕴涵的哲理是( )