根据故事内容填单词，补全句子

The Cat and the Bell

    There are some mice in a house. The host of the house gets a cat. The cat has killed many of the mice.

    Then the oldest mouse says, "All mice must come to my hole tonight. Let's put our head together and think what we can do to the cat."

    All the mice come. Many mice speak, but no one knows how to do. At last, a young mouse stands up and says, "We must put a bell on the cat. When the cat comes near, we shall hear the bell and run away. So the cat will not catch any more of us."

    But the old mouse asks, "Who will put the bell on the cat?"

    No mouse answers.

    The old mouse waits, but still no one answers.

    At last the old mouse says, "It is not hard to say things, but it is hard to do them."