单项选择题
A．Having a race in the snow. B．Visiting a friend in the Northeast. C．Traveling in the Northeast. D．Booking tickets for the winter holiday.
A．It will be revised. B．It has been canceled. C．It will be approved. D．It is under discussion.
A．It is seriously polluted. B．There are few cars and factories. C．The air is very clear. D．It remains what it was ten years ago.