The way people act in private is often quite different to how they act when in public.
人们私下的行为跟公共场合的行为是截然不同的。
I told him to stay for the weekend.
我告诉他留下来度周末。
If you want to send a letter to an office abroad that is in a different time zone, you can send a fax, and it will be received even though the office is not open.