阅读下面短文，从方框中选择适当的词语填空，方框中有两个词语为多余选项。
rule, none, again, note, first directly, another, set, out, gave up |
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."
如图所示为大爆炸宇宙模型半径、温度与时间之间的关系。