比如在纽约的话就用subway...

不过在地铁站看到的标志牌上面写的都是metro

都是通用的

在上海和香港看到的都是metro，感觉用metro好一点，underground和subway听上去都不怎么舒服。

我只想说我们这里英语书什么的 用的做多的是underground

subway是卖潜艇汉堡的

地下通道呢？

Subway - means subway trolley, or subway train. Yes, we have fast food store (that sells sandwiches or subs basically) called "Subway". But if you don't mention food, you say subway, people usually understand you are talking about public transportation.
Underground - it is clearly mean something underground: pipes, facilities, subway train running underground. By the way, we have subway trains running underground and on the street.
Metro - I guess it means Metropolitan. In other words, big city.
This is based on my best knowledge. I live in New England area, east coast of the United States.

只知道前两个，metro不是法语的地铁嘛。。

subway是美国用语……其他的是英国欧洲用语……香港不是英国殖民地么

subway在英国是地下行人通道

我快要七级了好开心
　　　　　 ——专业水贴小尾巴，不到十五非好汉！欧耶✌！