You can use this word around your friends, but not in formal situations or with strangers.

一般用在很随便的场合，朋友之间。

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Informal expressions like this can be used occasionally in formal situations, like the presentation example above, to make you sound relaxed, friendly and confident.

像这样的非正式短语informal expressions有时候也可以用在正式场合，如上例演讲中，令人感觉轻松，随意，也更自信。

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The formal title or family name is usually only used in formal situations, when meeting someone for the first time, or when speaking to someone like a professor, medical doctor, politician or VIP.

姓只用在正式的场合，例如第一次晤面时，跟专家，医生，政客或贵宾的交谈的时辰。

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With the ability to easily shoot in tough or formal situations, the photo possibilities keep growing.

ENGADGET: Olympus Stylus TG-625 Tough adds AF light for tricky shots in rough situations

And some situations require more formal behaviors that might be interpreted very differently in any other setting.

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