Four elements 四大元素
Teacher: What are the four elements of nature?
Student: Fire, air, earth, and….
Teacher: And what? Just think it over. What do you wash your hands with?
Student: Soap!
老师：什么是自然界的四大元素？
学生：火，空气，土，和….
老师：和什么？好好想想，你用什么洗手？
学生：肥皂！