小同轴电缆同轴对的特性阻抗一般标准定为（）Ω。
A.75
B.150
C.600
D.800
参考答案：A
To our great________, his parents were________at his mark. [ ]
A. surprises; surprised
B. surprises; surprising
C. surprise; surprised
D. surprise; surprising
两手对拉一弹簧秤，它的示数是10 N，这两手的拉力分别为( )
A．5 N，5 N
B．10 N，10 N
C．0 N，0 N
D．20 N，20 N
