作业帮A mobile phone is in fact a smail radio
来源：学生作业帮助网 编辑：作业帮 时间：2024/05/07 16:08:16
A mobile phone is in fact a smail radio
A mobile phone is in fact a smail radio
A mobile phone is in fact a smail radio
A mobile phone is in fact a small radio.A radio sends a person’s voice over a long way to another radio.A voice that is sent by radio is called a signal.A radio signal (信号) travels very quickly.
Only a few years ago,mobile phones were very large.They need very large batteries (电池).They had to be powerful to send their signal to far away places.This was because most cities had only one antenna tower for mobile phones.
Today’s mobile phones are small and easy to use.Now most cities have a lot of antenna towers,not just one.This means that each mobile phone doesn’t have to send its signal far away,so they don’t need to be so powerful.Mobile phones today use small batteries.A large city,where lots of mobile phones are used,can have hundreds of towers.
手机事实上就是一个小型的收音机。。
同意楼上，smail应该是small吧，这是扫描的？
你想问什么？？？
答案是BBCCA，也许你对答案有疑惑，但老师说答案没错。