1、You'd better use the electric cord if you want to use the radio since the batteries are run down.
如果你要聽收音機的話最好用電線，因為電池沒電了。

2、an electric cord used to extend the length of a power cord
延長電源線長度的電線。

3、an electric cord used to extend the length of a power cord.
延長電源線長度的電線。