No. 2 engine intensive vibration (severe vibration), reason unknown, we might shut down engine anytime.

第二发强烈抖动(严重抖动)，原因不明，我们随时可能关闭发动机。

youdao

For some unknown reason, many were discarded, often still intact, and thousands have been found all over the Near East.

由于一些未知原因，很多被丢弃的物品还是被完整地保存下来了，而在近东的各地有上千件这样的物品出土。

youdao

He was trying, for some unknown reason , to count the stars.

不知何故，他试图数星星。

《牛津词典》

The Republicans, for some unknown reason, decided to pass on fully emulating that system year.

FORBES: Obama's Not-So-Secret Weapon: Will He Use It to Help Power His New Mandate?

For some strange and unknown reason, the Small Business Administration has changed how it defines government support of small businesses, which will inadvertently destroy many small businesses, especially those supported through the Department of Energy.

FORBES: The Small Business Administration Decides to Hurt Small Businesses

For some unknown reason, it tries to force me to use Albany, NY as my departure airport for every search even though I do not live near Albany and have never flown in or out of the airport.

FORBES: Google Flights? Not Ready For Prime Time.