Giving a dog bad name and hang him 一旦给人加上一个坏名声,他就永远洗刷不掉/人言可畏 Seeing is believing 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
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！
