直到1920年才有了商业电台。

There were no commercial radio stations until 1920.

《柯林斯英汉双解大词典》

只有红灯闪亮时才有危及职工的险情。

Only if the red light comes on is there any danger to employees.

《牛津词典》

只有进行心脏移植，他才有望活下去。

His only chance of survival was a heart transplant.

《牛津词典》

But the problem is that they primarily relied on cheap labor, cheap products, manufacturing to get here.

但问题是，中国仍然依赖于廉价劳动力，廉价产品，才有今天的成就。

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Until you're a proficient reader of a language, writing in our language is a fool's errand.

你只有成为一个熟练的读者，才有可能成为一个好的作者。

英语阅读：技巧 - SpeakingMax英语口语达人

So, it's awkward to have to wait for a cow to get infected before you can vaccinate a population.

在给人们预防接种之前,你只有干等着,直到有一头奶牛感染了病毒才行

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