A wise man said: before you speak， let your words pass through three gates. At the first gate， ask yourself， "Is it true？" At the second gate， ask "Is it necessary？" At the third gate， ask， "Is it kind？"

Small changes in material design can lead to massive reductions in environmental impact.

人是理性动物，但当他被要求按照理性的要求行动时，可又要发脾气了。