One day, a student asked his teacher, "what is greed?" The teacher didn't answer his question____ , but asked the student to walk through the chocolate factory next to their school and pick out the biggest chocolate bar（条、块） he could find．But there was a ____: as he passed through the factory, he could not turn back.

    The student went to the chocolate factory. As he walked, he saw a large chocolate bar. He liked it, but thought he might be able to find an even bigger one if he kept going. He kept walking and saw ____ chocolate bar. This one was a little bigger. But ____, he thought he could find an even bigger one if he kept going. As he neared the end of the factory, he saw fewer chocolate bars, and ____ of them were as large as the earlier ones. He started to regret his decision to keep going. Finally, he ____. He went back to his teacher empty-handed and explained what had happened.

    The teacher told him, "You liked the ____chocolate bar, but you kept looking for a bigger one. And later, you realized that you had given up the best chocolate bar because you thought you could do better. That is called greed."