[没齿难忘 / 沒齒難忘, mò chǐ nán wàngㄇㄛˋ ㄔˇ ㄋㄢˊ ㄨㄤˋ] hard to forget even after one's teeth fall out (成语 saw); to remember a benefactor as long as one lives; undying gratitude#103893
[没齿不忘 / 沒齒不忘, mò chǐ bù wàngㄇㄛˋ ㄔˇ ㄅㄨˋ ㄨㄤˋ] hard to forget even after one's teeth fall out (成语 saw); to remember a benefactor as long as one lives; undying gratitude#180616
[咬人狗儿不露齿 / 咬人狗兒不露齒, yǎo rén gǒu r bù lù chǐㄧㄠˇ ㄖㄣˊ ㄍㄡˇ ㄦ˙ ㄅㄨˋ ㄌㄨˋ ㄔˇ] the dog that bites does not show its fangs (俗语 saying); fig. You can't tell the really dangerous enemy from his external appearance., See Also: 俗语