【单选题】对称三相负载星形接于三相电源上, 正确的说法是
B.
线电压是相电压的 倍,线电压超前相电压30°
C.
相电压是线电压的 倍,相电压超前线电压30°
D.
线电流是相电流的 倍,线电流超前相电流30°
【单选题】随着机器人在中国的快速发展,国际品牌ABB机器人1994年在中国 建立国际领先的机器人生产线。
【单选题】Mrs. Smith saw ______ in the old lady' handbag.
B.
a wad of ten pound notes
【单选题】对称三相负载星形接于三相电源上, 正确的说法是
B.
线电压是相电压的根号3倍,线电压超前相电压30度
C.
相电压是线电压的根号3倍,相电压超前线电压30度
D.
线电流是相电流的根号3倍,线电流超前相电流30度
【单选题】From 2000 to 2010, the yen/dollar exchange rate fell from 240 yen/dollar to 102 yen/dollar, while the dollar/pound exchange rate fell from 2.22 dollar/pound to 1.62 dollar/pound. As a result,
A.
the dollar appreciated relative to the yen, but depreciated relative to the pound.
B.
the dollar depreciated relative to the yen, but appreciated relative to the pound.
C.
the dollar appreciated relative to both the yen and the pound.
D.
the dollar depreciated relative to both the yen and the pound.
【单选题】There is two______of lubricating(润滑)oil in the container.
【单选题】对称三相负载星形接于三相电源上, 正确的说法是