Tim and Jack are good friends.Sometimes they are friendly to each other,but sometimes they are not.
One day they go out for a walk.At noon they are hungry and they go to a restaurant for lunch.Tim says."Please bring us two oranges first."When the waiter puts two oranges on the table.Jack takes a big one.Tim gets unhappy,"You're not polite,Jack.Why don't you take the small one?"Tim says.
"But I'm right."says Jack with a smile."If I let you take first,which one will you take?" "Of course I'll take the small one,"says Tim."Yes,"Jack says,"if you take the small one,the big one will still be mine.Don't you think so ?"oh..."Tim can't answer.