You must play a diamond if you have one.

如果你有方块就必须出。

《牛津词典》

Those who want to ban the bomb for American citizens claim that if you have one locked in the cabinet, with the fuse in a drawer, you would never be able to assemble it in time to stop an intruder.

那些希望禁止美国公民使用这种炸弹的人声称，如果你把一枚炸弹锁在柜子里，把导火线放在抽屉里，你就永远无法及时组装起来，阻止入侵者。

youdao

You must play a spade if you have one.

你如果有黑桃牌，就必须打出来。

《牛津词典》

If you plant some seeds every week or two, you will have crops ready to eat one after another.

VOA: special.2009.04.28

This is incredibly important because if you picture having a double bond in a very large molecule, you could have all sorts of other atoms off this way and all sorts of other atoms off this way, and you can picture the shape would be very different if you have one confirmation versus another confirmation.

这是十分重要的,因为如果你想象在一个大分子里有一个双键，你可以在这里有各种各样的其它原子,在这里也有各种各样的其它原子，你可以想象一个构型,和另外一个构型之间的形状差别是非常大的。

麻省理工公开课 - 化学原理课程节选

And it will be a topic that you can discuss with your exchange partner if you have one.

如果你有语伴的话，这将是你们可以讨论的一个话题。

学外语的时候 - SpeakingMax英语口语达人

Cardiac rehabilitation isn't appropriate for everyone, though, even if you have one of these conditions.

CNN: updated

Check your local newspaper (if you have one) or, better yet, realclearmarkets.com and see.

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If you have one, you may want to ask your financial advisor four questions.

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