How to ask to buy and where can you buy underground tube top up cards for Beijing underground? I am studying in China for 6 months and would like to buy a underground tube top up card for Beijing so I can use the tube and use the buses. It will help me to use them quicker instead of always having to get 2 yuan and buy a ticket and on the buses I think you get a cheaper fare so it would be very helpful if anyone could explain how I go about this process 谢谢 ^ ^