Student or Learner
"busy" is either "crowded" or "having a lot of things to do", which do you think this means?
110)China is a very large country with many many people. I'm from Zhengzhou...It is a big city with about two million people. Zhengzhou is a busy city...
It could mean one of several things, all related. The context will make it reasonably clear.
Incidentally, I don't think we say that 'busy' cities 'have a lot of things to do'.