If you put your trust in me, I will not let you down.

你要是信赖我，我就不会让你失望。

《牛津词典》

If anyone here has problems with your shoes, please come to me and I will not let you down.

如果这里有人的鞋子有问题，请来找我，我不会让你失望的。

youdao

However, if you catch my hand instead, no matter what happens to me, you will not let me fall down..

但是，如果你握住我的手，不管发生什么事情，你都不会让我掉下去的。

youdao

"My mother told me not to talk too long today and Barbara, I will not let you down, " Clinton quipped Thursday, prompting laughs from Hillary Clinton.

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