observe relates to a often followed treatment or pattern in conducting actions: It can be his apply to verify all statements.知乎，让每一次点击都充满意义 —�?欢迎来到知乎，发现问题背后的世界。知乎，让每一次点击都充满意义 —�?欢迎来到知乎，发现问题背后的世界。#banner #flag #flag def