Mobike has just become popular in China recently, but it's not always as good as expected. Mobike is a kind of shared public bicycle in China, people only need to pay a very small amount of money to use it. And you can park it in any public areas as long as it won't block the way. It's very convenient for people's travelling outside in a city. It can also help reduce the traffic jam. However every coin has two sides. In one morning several days ago, I left home to work. As usual, I found a mobike near my home, then I used my cellphone to scan the QR code, the bicycle was unlocked. I sat on the bike and tried to ride it. But unfortunately, it didn't move. I got off the bike and looked down into the bike, then I found this bike didn't have chains! Today, I scanned three bicycles, just because 2 of them were really hard to ride, and the third one couldn't be unlocked automatically. Luckily the fourth one was good, I rode fast trying to catch up with my shuttle bus. When I arrived at the intersection, I was blocked by the red traffic light. At this time, I found the shuttle bus started and moved slowly passing away in front of me. What a pity! I had to take the subway to work today.