Definition: to disappoint someone by failing to do what you agreed to do Level: B2
他承诺帮助这个项目，所以他不能让他的团队失望。
He promised to help with the project, so he can't ___let his team ___down.
她向我们保证不会让我们失望。
She assured us that she wouldn't ___let us ___down.
如果你承诺了一个截止日期，确保不要让你的老板失望。
If you commit to a deadline, make sure you don't ___let your boss ___down.
