A boy couldn't speak when he was 3 years old. A lot of people thought he was a foolish boy. When the boy was 9 years old, he could speak but he still couldn't speak well. His teacher didn't like him at all and his classmates laughed at him. He felt very sad, One day his father had a walk with him. They went to a wood and there were a lot of trees there. Then his father took him to two trees and said to him.“Boy, this tree is sabal (菜棕，一种树的名字）and this tree is fir(冷杉). Sabal grows very quickly at first but a few years later, it will stop growing, so the tallest Sabal can't reach(达到）ten meters. But the fir is different, it grows very slowly at first but it never stops growing so it can grow very tall."

    Then his father took him to another fir. It was so tall, so strong. It can reach the sky. The father said to his son, “Son, you are the fir."The boy understood his father's words. The boy became a very great scientist. Do you know who he is? He is the world-famous scientist. His name is Einstein.

如果a和b是互质数，那么a和b没有公约数．

在第53届苏州世乒赛女单决赛中，中国选手丁宁在0：2落后且右脚扭伤的情况下，“希望能战斗到最后”的强烈信念使她越战越勇，最终斩获冠军。丁宁的事迹告诉我们（    ）