so many houses have burglar alarms nowadays.it is a()of the time.A sign B signal

分类: 作业答案 • 2021-12-03 17:04:04

问题描述：

so many houses have burglar alarms nowadays.it is a()of the time.A sign B signal
AB那个正确为什么

答

a 是正确的
a是标志象征
b是信号的意思多指电子信号