【简答题】如图所示的电路,R=4Ω,另一个电阻Rx和电源电压U未知,当闭合开关 S 2 , 而 S 1 、S 3 断开时,电流表的示数为0.5A;如果断开 S 2 ,闭合开关 S 1 、S 3 时,电流示数为2.25A。 求:电阻Rx的阻值。
【简答题】整 流 滤 波 电 路 如 图 5 所 示,二 极 管 是 理 想 元 件 , 变压器副边电压有效值 U 2 =10V , 求: (1) 开 关 S1 闭 合、S2 断 开时, 直 流 电流表的 读 数 : (2) 开关 S1 断 开、S2 闭 合 时, 直 流 电压表的 读 数 : (3) 开 关 S1 、S2 均 闭 合 时, 直 流 电压表的 读 数 :
【判断题】叠加定理只适用于线性电路的电压和电流的计算。不适用于非线性电路。也不适用 于线性电路的功率计算。
【简答题】FDI has grown more rapidly for several reasons. First, business firms still fear _______________ pressure. Second, the increase in FDI is being driven by the political and _______________ changes in m...
【判断题】叠加定理只适用于线性电路的电压和电流的计算,不适用于非线性电路,也不适用于线性电路的功率计算。
【单选题】导游服务是导游人员通过向游客提供劳务而创造特殊( )的劳动。
【简答题】如图所示的电路,R1=9Ω,R2=6Ω,R3=4Ω。开关S1、S2均断开时,电压表的示数为5.4V。 求:(1)开关S1、S2均闭合时,电流表、电压表的示数。 (2)仅合上开关S2时,电压表、电压表的示数。
【单选题】Many of the early U.S. railroad companies defined themselves as being in the railroad business instead of being in the transportation needs business. These companies used ______________.
A.
resource-based missions
B.
customer-oriented missions
C.
product-oriented missions
【单选题】If the early U.S. railroad companies defined themselves as being in the transportation needs business, which is more customer-oriented, they might have successfully moved into what product/service bef...
A.
Commercial aviation (such as Delta and United)
B.
Modern shipping and logistics (such as FedEx and UPS)
C.
International cargo containers on large ocean ships
D.
Fuel efficient automobiles (such as Toyota and Ford)