装有ABS系统的汽车，轮速传感器向电脑发出（）信号。
A.电流
B.频率
C.电阻
D.电压
参考答案：B
They tried to find a table for two. But they were all ______.
A．given away
B．kept away
C．taken up
D．used up
每（）个月测试一次阳极地床接地电阻，两次测试间隔不超过9个月。
A.1
B.2
C.3
D.6
