【简答题】Whales live in the ocean, but they are not fish. They are warm-blooded mammals and must have air to breathe. The babies are born alive and drink milk from the mother's body. It took millions of years ...
【单选题】Some people think they have an answer to the troubles of automobile crowding and dirty air in large cities. Their answer is the bicycle, or 'bike.' In a great many cities, hundreds of people ride bicy...