She had always seemed friendly until suddenly she began to show her teeth.

她看起来是客客气气的，一旦脾气发作起来，就张牙露齿不那么客气了。

《新英汉大辞典》

Consumers had assumed wine served in screw-top bottles was inferior—until suddenly they were so ubiquitous and acceptable (and easier to open) that many wine lovers came to prefer them.

消费者们原来觉得把酒盛在瓶盖是螺丝拧的瓶子里是不上档次的——直到突然满大街都是这样的装法（而且的确好开多了），然后酒徒们也开始喜欢上了这种包装。

youdao

Perhaps a design works so well. It is adopted elsewhere again and again, with seemingly harmless improvements, until, suddenly, it does not work at all anymore.

一种设计效果很好，反复应用于其他地方，加上一些看似没什么影响的改进，突然有一天它就不奏效了。

youdao

The mathematical theory of probability was unknown until that time and you can see that insurance suddenly made an appearance at that time.

在那之前,概率的数学理论,是不存在的,而随着概率论的出现,保险业也突然出现了

耶鲁公开课 - 金融市场课程节选

Most remained mired in subsistence level agriculture until suddenly advances in the Anglosphere catapulted living standards forward.

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Traders whose approaches go in and out of style, until suddenly they are 80 and their tack seems to work, once again.

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Their new products are terribly useful, until suddenly they completely stink.

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