In order to know a man, you have only travel with him for a week.
その人がどんな人か知りたければ一週間も旅行を一緒にすれば良い。
you have only to
All you have only to do is
https://tamagodana-study.me/only-to/
as long as,if only,only ifhttps://ameblo.jp/phil-mason/entry-12368960056.html