传输2M电路故障判断时常用的测试方法是（）.
A.环回测试
B.电压测量
C.电阻测试
D.保护测试
参考答案：A
把2.9543保留整数约是______，保留一位小数约是______，精确到百分位约是______．
Eton College in England was__________ in 1440 by King Henry VI to give free education to poorsluclents.[ ]
A. cleaned up
B. set up
C. fixed up
D. cheered up.
