[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