There is a kind of pretty popular transportation in every big city. It's (地铁). No matter how far you are from the (中心的) part of the city, you can take it to many places in your city. It's very (方便的) for everyone to get everywhere. It's just like a(n) (明信片) of a big city. If you want to take it, you must know something about it. First, you must know the right (方向), and then you are able to get on it. Or you may go to wrong places. Next, you should learn to be (礼貌的) to let others get on or off first. There are some signs that (引导) you to wait for it. That means you should wait for it at the (正确的)places. However, some people complain that there are no (洗手间) on it. Experts say that there is no need to set them up. After all, everyone doesn't (花费) much time on it.
