He could react jealously when and if another child comes on the scene.

如果有别的孩子加入其中，他可能会表现得相当嫉妒。

《柯林斯英汉双解大词典》

You also need to think about when and if you can reason with an assailant.

你也得考虑何时以及是否可以跟侵犯者讲理。

youdao

"We'll cross that bridge when and if we get to it," is all Mr Sanford's spokesman has said.

“船到桥头自然直”，这就是目前桑福德发言人所透露的全部信息。

youdao

So if you play cat and mouse with someone, you change between different kinds of behavior when dealing with another person.

VOA: special.2009.09.27

And in fact, if I substitute, I can solve for this I'm done when this is equal to 1.

到1的时候就完成了,当你把所有的都替代完以后。

麻省理工公开课 - 计算机科学及编程导论课程节选

So when you go, for example, in your neighborhood, if there's one coffee shop and you like their coffee,

所以，举个例子来说，如果你住的小区有个咖啡店，而你又喜欢喝咖啡的话，你可以去，

在英语系国家 - SpeakingMax英语口语达人

Resilient systems and communities can recover more quickly when and if disaster does strike.

FORBES: Cyberwar Hype Comes Under Increasing Scrutiny

Officials say they will cross that bridge when and if they come to it.

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When and if Mickelson or his kids spend, we could tax him or them then.

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