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goes without saying; needless to say; obvious
健康が大切なのは言うまでもない。
It goes without saying that health is important.
準備が重要であることは言うまでもないことだ。
It goes without saying that preparation is important.
彼の功績が偉大であったことは言うまでもないだろう。
It goes without saying that his achievements were great.