Little Smart or Xiaolingtong is becoming more and more popular in China. But you can use it only in your city. If you go to another city, it will have no use. It looks like a mobile phone, but the service( )is quite cheap. We only need to pay about 20 yuan a month for the line and about 0.1 yuan each minute for the talk. What's more, you don't have to pay any money when someone else calls you. But little Smart is not really so smart. Users often complain about( ) its bad voice. " I can't make or get a phone call when I am on a bus," a person in Hangzhou said. Scientists are trying their best to make Little Smart smarter. And the latest Little Smart even has a color screen. If someone calls you by your Little Smart, you should pay  _  .
20 yaun 0.1 yuan 0.1 youan a minute nothing