认为理所当然用英语怎么说

"理所当然"用英语可以说成"It goes without saying"或"It is self-evident."

来源：这个短语最早被认为是英国哲学家John Locke在17世纪使用。

英文例句：

It goes without saying that we need to be on time for the meeting.
中文翻译：会议需要准时参加这是理所当然的。

It is self-evident that eating a healthy diet is important for good health.
中文翻译：健康饮食对健康有益这是不言而喻的。