Do you like riding bikes? Mobike is one of the most popular bikes in China. It is a great invention nowadays. You can rent(租用)and return the bike easily and quickly. When you want to use it, you should use your phone to scan the QR code(二维码)on the bike, open the smart lock, and then you can ride the bike. When you want to return it, put it in special area on the roadside and close the lock. It usually costs(花费)you only one yuan an hour. It is good for our health. Everyone can ride the bike. But, if you are under 12 years old, you can't ride the bike. It's dangerous. There are too many cars on the road. Be careful when you ride the bike.