理所当然用英语怎么说？

用英语可以说“It goes without saying” 或者 “It is self-evident.”

来源：

这两个短语都是从拉丁语转译过来的。“It goes without saying” 来自拉丁语的 “sine qua non,” 意思是“没有这个就不可能”，表示某事理所当然，不需要解释。“It is self-evident” 来自拉丁语的 “per se,” 意思是“本身”，表示某事显而易见，不需要证明。

例句：

It goes without saying that everyone should wear a seatbelt while driving. (理所当然，驾驶时所有人都应该系安全带。)

It is self-evident that the Earth revolves around the Sun. (显然，地球绕太阳转。)