搜题请搜索小程序“爱下问搜题”
问题 单项选择题

母线差动、变压器差动和发变组差动保护各支路的电流互感器应优先选用误差（）和（）的电流互感器。

A.限制系数变比大

B.限制系数饱和电压较高

C.允许系数饱和电压较低

D.允许系数饱和电压较高

答案

参考答案：B

填空题

因式分解：a3-a=（    ）
查看答案
单项选择题

One of the most convenient and cheapest ways to see America is by riding a Greyhound bus. This interstate bus system connects all major cities in the United States, (52) people with frequent and convenient service. The bus system even has an international service (53) makes connection with cities in Canada and Mexico.

Its network even extends to some of the smaller towns and out-of-the-way communities (54) the great interior of the country. Traveling by bus may (55) longer than flying by plane, but the terminals are located in the center of most cities and there is (56) to the downtown area. These buses are comfortable and air-conditioned. They are all equipped with toilets in the rear to (57) the convenience of the passengers, but there are some very severe (58) of conduct which are strictly enforced. On all buses (59) is forbidden and the consumption of alcoholic drinks is not allowed.

(60) bus travel may not be suited to everyone’s taste, it affords budget travelers the (61) to see America in comfort and safety and at a leisurely unhurried pace.

54().

A.for 

B.along 

C.in 

D.from
查看答案