测量声速在不同介质中的波速时,不需要更换信号源上的“声速传播介质”属性。
A. 对
B. 错
相位法测量中两个相互垂直的简谐振动的频率相等。
A. 对
B. 错
The earliest Internet was
ARPAnet
B. MILnet
C. NSFnet
D. ANSnet
According to the size of the network,the network can be divided into
A. WAN CAN LAN
B. WAN MAN LAN
C. WAN MAN TAN
D. GAN MAN LAN