give off和give out都有“发出”的意思,那么电台发出信号应用哪一个?有关这个的一条选择题我选错了,至今搞不清它们的区别,谢谢（请别再用百度词典上的解释,那个我看过了,还是没什么帮助）.

give off
发出; 放出（气味）; 散发出; 放射出
When nitric acid is poured on copper, a brown vapor gives off.
将硝酸倒在铜上, 会散发出一种棕色的蒸气。
Rotten eggs give off a bad smell.
臭蛋散发出难闻的气味。
give out
1.分发; 散发
They stood there, giving out the leaflets to the passers-by.
他们站在那里, 向过路人散发传单。
2.公布; 宣布
The news of the event was given out over the radio.
关于这个事件的消息通过无线电发表了。
3.耗尽; 用完
He plans to stay there until his money gives out.
他计划在那里待到钱花完为止。
4.停止起作用
We had hardly started from home when the engine gave out.
我们刚刚离开家, 发动机就失灵了。
根据第二点，所以是give out

give out

give out有指用完.耗尽 之意
give off指放出声.光.热.气体等
对于此种介词辨析问题可以多找出例句或有关的英语原文多读多倍背，，，培养语感，到时
可接着语感选出。。太抠细节容易钻牛角尖。。

give off

give out 不仅有发出的意思,还有泄漏秘密的含义
giveoff 是发出信号的意思

最简单的回答就是 电台发出的是信号 记住信号就好了的），所以用give out
give off
发出; 放出（气味）; 散发出; 放射出
When nitric acid is poured on copper, a brown vapor gives off.
将硝酸倒在铜上, 会散发出一种棕色的蒸气。
Rotten eggs give off a bad smell.
臭蛋散发出难闻的气味。
give out
1.分发; 散发
They stood there, giving out the leaflets to the passers-by.
他们站在那里, 向过路人散发传单。
2.公布; 宣布
The news of the event was given out over the radio.
关于这个事件的消息通过无线电发表了。
3.耗尽; 用完
He plans to stay there until his money gives out.
他计划在那里待到钱花完为止。
4.停止起作用
We had hardly started from home when the engine gave out.
我们刚刚离开家, 发动机就失灵了。