There's not a liberal America and a conservative America - there's the United States of America.

To signal an emergency， use the rule of three； 3 shouts， 3 horn blasts， or 3 whistles.

Our greatest ability as humans is not to change the world, but to change ourselves.

忘记不是记忆力的问题，而是注意力的问题。

对探究的自由必须没有任何障碍……科学中没有教条的位置。