Mr. Green lives in a big city with his wife and two children. One morning Mr. Green takes his new car and washes it when a friend comes. The friend stops and looks at the new car for a minute. Then he asks, "That's a new car. Is it yours? "
"Sometimes." Mr. Green answers.
   The friend is surprised (惊奇). "Sometimes? " he says. "What do you mean?" Mr. Green answers slowly, "Well, when there is a party in town, my daughter Jean drives it. When there is a football, it's my son Jim's turn. When I washes it and it looks very nice and clean, my wife Linda uses it. And when it needs cleaning. It's mine. Choose the correct answer.