seeing is believing

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said to mean that if you see something yourself, you will believe it to exist or be true, despite the fact that it is extremely unusual or unexpected

意思是如果你自己看到某件事，你就会相信它存在或是真的，尽管它是极其不寻常或出乎意料的;眼见为实、百闻不如一见

I never thought Mark would get out of bed before lunchtime on a Saturday, but seeing is believing!

我从没想到马克星期六会在午饭前起床，真是眼见为实!