'I won't let you down,' he replied.

“我不会让你失望的。”他回答说。

《牛津词典》

Don't worry, Xiao, I won't let you down.

不要担心，肖，我不会让你失望的。

《柯林斯英汉双解大词典》

'I won't let you down,' he replied confidently.

他信心十足地答道：“我不会让你失望的。”

《牛津词典》

ERIC: Why you shooting down my game?Let a playa play. MIKE: Yeah, okay.What you playing at, T-Ball?

VOA: standard.other

You rely on publishers and then they let you down.

你依赖出版商,但他们让你失望。

耶鲁公开课 - 1945年后的美国小说课程节选

Let's say, you're walking down the street, passed a house that looks really really familiar.

假设，你正沿着街走着，路过一栋房子时，你觉得特别眼熟。

I used to 课堂 - SpeakingMax英语口语达人

Obama that the vibrant women of Africa are here, and we are not going to let you down.

WHITEHOUSE: African Women Entrepreneurs Visit the White House

This boy, this son of ours, in not going to let you down.

CNN: For Bush, a family affair in New Hampshire

With people who let you down, talk straight about your expectations for their performance and your hopes for their improvement.

FORBES: What David Petraeus Teaches All of Us About Trust