Expand knowledge:
First, buy a train ticket.
It is best to buy train tickets through official website.
Now the time to buy tickets is two months in advance. Pay attention to the time of buying tickets.
Second, the website of 12306 can't be opened.
It is because there are too many people visiting the website at a time, which leads to the server.
It's because the computer network is too bad to connect to the Internet.