one day

いつか

いつかは明示せず、未来のある時に。

やさしい英語で： At a future time, without saying exactly when.

• One day I will visit Japan.
• She hopes to own a house one day.
• Will we live on Mars one day?

類義語： someday

よく使う表現： one day soon, maybe one day

一日

一日だけの期間にわたって。

やさしい英語で： For a period of just one day.

• We stayed one day.
• The repairs took just one day.
• Can you wait one day longer?

類義語： byembye, hereafter, later, someday

よく使う表現： only one day, one day longer

ある日

いつかは明示せず、過去のある日に。

やさしい英語で： On a particular day in the past, without saying exactly which day.

• One day I found a kitten.
• We were walking home one day when it started snowing.
• One day she received a surprising letter.

類義語： once

よく使う表現： one day last summer, one day someone