The recipe for their drink is a closely guarded trade secret.

他们饮料的配方是严格保守的商业秘密。

《牛津词典》

My grandmother's recipe for chocolate cake is a secret.

我奶奶的巧克力蛋糕的配方是个秘密。

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My father had a secret recipe for noodle soup. This is how we became the best noodle restaurant in town!

我爸爸有这汤面的独门秘方。就是这样我们成了本地最有名的面店！

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There is a widespread belief that China has found a secret recipe for growth which basically involves building lots of stuff - infrastructure, railways, airports, roads and the like.

BBC: China to the UK's aid?

As the head of Google's antiwebspam team, he's rewriting the complex set of rules for ranking Web pages based on their relevance to a given query, which is the company's DNA, its single most important product and a trade secret more closely guarded than the recipe for Coke.

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