标幺制有什么好处？
参考答案：易于比较电力系统各元件的特性及参数，能够简化计算公式，能在一定程度上简化计算工作。
In the following essay, each blank has four choices. Choose the best answer and write down on the answer sheet.
In low - speed network, it is usually adequate to wait for congestion to occur and then react to it by telling the source of packets to slow down. In high - speed networks, this approach often works poorly, because in the (1) between sending the notification and notification arriving at the source, thousands of additional (2) may arrive. In ATM network, a major tool for preventing (3) is (4) control. When a host wants a new virtual (5) , it must describe the traffic to be offered and the service expected.
3（）
A．collision
B．congestion
C．drop
D．delay
火星的质量是地球质量的m倍，它的公转轨道的半径是地球公转轨道半径的n倍，则太阳对火星的引力是对地球引力的多少倍（ ）
A．mn倍
B．mn2倍
C．mn-2倍
D．n3m-1
