阅读短文, 然后从方框中选出可以填入文中空白处的单词.

used, just, line, heard, happy, came, piece,from, well

      We can often see dog owners taking their dogs for a walk. But have you  of taking penguins(企鹅) for a walk? Here is a of news from Japan. In Tokyo Zoo, penguins go out for a walk inevery day. It is said that this can make them happy and stop them

being homesick(想家的). The penguins in the zoo didn't eat and were not kind to workers when they first came to the zoo, maybe they were not to the life in the zoo. So the zookeepersup with this good idea.Theylet them walk as they did in South Pole. Now, all these penguins have become .