In case of suspicions or irregularities an unannounced inspection may take place at any time.

在怀疑或情况不规律，任何时候都可能会抽检。

youdao

If a restaurant doesn't earn an a during its first inspection, it's considered scored but ungraded and a Health Department official will show up unannounced to re-inspect and possibly award a grade.

如果一家餐馆不能在第一次检查时拿到A级，卫生署只会打分却不会分级，以后卫生署的检查员会在没有事前通知的情况下再度检查，然后以此为基础对餐馆进行分级。

youdao

In retirement, he had a habit of popping up, particularly in booming Guangdong province, on unannounced "inspection" Tours.

退休期间，他还不时露面，尤其在繁荣的广东省，来个突然的“视察工作”之行。

youdao

The Bell 430 helicopter disappeared while flying through a heavy rain storm, en route to an unannounced inspection of a local district.

VOA: standard.2009.09.03

It follows an eight-day unannounced inspection of the department by five Ofsted officers in January.

BBC: Tyler Whelan

Another unannounced inspection found required standards in maternity services at the hospital were now being met.

BBC: Queen's Hospital in Romford

The report released on Wednesday details the unannounced inspection which was carried out between 3 and 13 July.

BBC: Gloucester Prison