Leaving the most important tip for being a good guest is to know when to say goodbye.

作为一个好客人，给你最重要的提示是知道什么时候说再见。

youdao

In order to know when to say no, you need to know what's on your plate.

为了知道什么时候用得着说“不”，你得了解你现在已经揽了哪些活了。

youdao

We publish guidelines about when to say you're an IBM employee, what kind of material is appropriate and inappropriate to share, etc.

我们制订了一些规定，例如明确了员工在哪些场合下可以表明自己IBM员工的身份；哪些信息是适合分享的、哪些信息则不然等。

youdao

You might say when I wear my best clothes, I am dressed to the nines or dressed to the teeth.

VOA: special.2010.05.09

That is to say that when we think we're telling the truth we're actually using worn-out figures of speech.

也就是说我们认为我们在讲述真理的时候,我们实际上却在使用一些陈腐的修辞手法。

耶鲁公开课 - 文学理论导论课程节选

When I say dirty, I am referring mostly to like a graffiti. There's a lot of graffiti on walls, on buildings.

我说的脏，主要指的是涂鸦。大楼墙上到处画满了乱七八糟的涂鸦。

哈莱姆很独特 - SpeakingMax英语口语达人

The test of his entrepreneurial model will be whether he will know when to say good-bye.

ECONOMIST: Johnny Appleseed.com

When to say it is often just as important as what you say or where you say it.

FORBES: The Alarming Rise Of 'Digital And Content Pollution'

Yes, I've had to learn how to know when to speak and what to say, when to say it.

NPR: Hip Hop Takes on Diplomatic Role with State Department