句子使用情态动词表达劝诫和要求，语气明确有力。
When Einstein was sixteen, he had failed several subjects due to spending all his time with a mischievous group of children. One weekend morning, he was holding a fishing rod, ready to go fishing with them, when his father stopped him and calmly said, “Einstein, you play all day and fail your classes. Your mother and I are very concerned about your future.”
“What's there to worry about? Jack and Robert also failed, yet they still go fishing,” Einstein replied.
“My child, You must not think like that,” his father said lovingly. “In our hometown, there is a fable I want you to listen to carefully.”
“Two cats were playing on a roof when one accidentally fell, holding the other, into a chimney. When they climbed out, one cat's face was covered in soot, while the other's face was clean. The clean cat saw the soot-covered cat and thought its own face was also dirty and ugly, so it rushed to the river to wash. Meanwhile, the black-faced cat saw the clean cat and assumed its face was clean too, strutting along the street.”
“Einstein, no one can be your mirror; only you can be your own mirror. Using others as your mirror may turn even a genius into a fool.” Hearing this, Einstein felt ashamed, put down his fishing rod, and returned to his room.
爱因斯坦16岁那年，由于整日与同一群调皮孩子玩耍，导致几门功课不及格。一个周末的早晨，爱因斯坦正拿着钓鱼竿准备和那群孩子一起去钓鱼，父亲拦住了他，心平气和地说：“爱因斯坦，你整天贪玩，功课不及格，我和你母亲很为你的前途担忧。”
“有什么好担忧的？杰克和罗伯特他们也没及格，不照样去钓鱼吗？”
“孩子，你千万不能这样想。”父亲充满关爱地望着爱因斯坦说：“在我们故乡流传着这样一个寓言，我希望你能认真听一听。”
“有两只猫在屋顶上玩耍，一不小心，一只猫抱着另一只猫掉进了烟囱。当两只猫从烟囱爬出来时，一只猫的脸上沾满了黑烟，而另一只猫的脸上却干干净净。干净的猫看到满脸黑灰的猫，以为自己的脸也又脏又丑，便快步跑到河边洗脸。而黑脸猫看到干净的猫，以为自己的脸也是干净的，就大摇大摆地在街上闲逛。”
“爱因斯坦，谁也不能成为你的镜子，只有自己才是自己的镜子。拿别人做自己的镜子，天才也许会变成傻瓜。”爱因斯坦听后，羞愧地放下鱼竿，回到自己的小屋里。