The location of the ship is a closely guarded secret.

那艘船的方位是高度机密。

《牛津词典》

These days, the Coca-Cola recipe is a closely guarded secret.

如今，可口可乐的配方是一个严格保守的秘密。

youdao

In the past, information about orbits was a closely guarded secret.

在过去，关于轨道的信息是严格警戒的秘密。

youdao

Holbrooke's location in Pakistan personally coming here is a closely guarded secret, given the heightened security concerns following deadly terrorist attacks in Lahore and Peshawar,last week.

VOA: standard.2009.06.03

For years,this had been a closely guarded family secret.

VOA: special.2009.08.23

Her conclusions were a closely guarded secret until a public meeting on Tuesday night.

BBC: Bannockburn site revisited

The number of Sentinels that the Air Force operates remains a closely guarded secret.

WSJ: Iran Says It Shot Down Unmanned U.S. Plane

The sad truth is that good fishing is always private, extremely expensive or a closely guarded secret.

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