Well this can come in a flash or take a good amount of time.

理想可能来自灵光一现，也可能需要长时间的努力。

youdao

The answer had come to him in a flash.

他一下子就有了答案。

《柯林斯英汉双解大词典》

A flash mob is a group of people who come together suddenly in a public place, do something unusual for a short period of time, and then quickly break up.

快闪族，是指一群人突然在公共场所聚集，在短时间内做一些不寻常的事情，然后迅速散开。

youdao

It's real easy when you announce your campaign to come out like a flash in a pan.

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Many of the companies that will go public in the year to come are far more substantial than the dot-coms that rose to fame in a flash and disappeared in a poof.

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Most Americans are more concerned about the games on their iPhone, the NFL labor strike, and assorted other bread and circuses, than the very real prospect that our 235-year-long narrative of increasing dominance could be suddenly over in a flash should we default or come close to defaulting on our debt.

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