You use whenever to refer to any time or every time that something happens or is true.
Whenever I talked to him, he seemed like a pretty regular guy.
我无论什么时候同他讲话,他都表现得像个很正常的人。
You can stay at my cottage in the country whenever you like.
只要你愿意,无论什么时候都可以住在我乡下的小屋里。
You use whenever to refer to a time that you do not know or are not sure about.
He married Miss Vancouver in 1963, or whenever it was.
他好像在1963年或什么时候娶了温哥华小姐。