单项选择.
He is a teacher, he works in a ______.
答案:C
解方程:
2x-5=15;
x+40%x=4.2;
0.4:x=8:11.
电话接口模块用于和无线通信系统及录音系统连接,采用()接口相连。
A.RS422
B.RJ11
C.RJ45
D.BNC