∵(±18)2=164,
∴平方得164的数是±18.
故填空答案:±18.
可视电话需要主被叫双方终端具有视频功能,是音频和视频的同步通信。
____is very important for Chinese people. [ ]
A. The spring festival
B. Spring festival
C. Spring Festival
D. The Spring Festival