public String inCar(String carID) {
		
		String txt="";
		if(isFull()) {
			txt="对不起，停车场已满。";
			return txt;
		}
		if(carID.equals("")){
			txt="请输入你停的车的车牌号：";
			return txt;
		}
		
		if(contain(new Ticket(carID))) {
			txt="你要停的车已经停在我们的停车场里了。";
			return txt;
		}
		Ticket ticket = in(new Car(carID));
		txt = "OK，请记住你的取车票据号[" + ticket.getCode() + "]，";
		return txt;
	}