-_______students are there in your class, Mr Li?  -Fifty. 

I don’t think he is right, ________?

---_______ your friend have a tennis racket?---No, but he has a great ping-pong bat collection.

 —      is it from your home to your school?—It takes about twenty minutes by bike. 

---_____ does she chat with friends on the Internet?--- Once a week.