Turn that radio down ...(Para. 4)
Meaning: Reduce the sound of the radio ...
turn down: reduce (a flame, a sound, etc.) usually by moving a switch
Please turn the television down. I'm trying to sleep.
请把电视机关小点声,我想睡觉了。
n. 开关,转换,鞭子
v. 转换,改变,交换