他们已经搞清原因。

They have cleared up the cause.

youdao

以后你的医生让你做检查的时候，你要问清原因。

Until then, the next time your doctor wants to order a test, ask why.

youdao

我的双眼总是饱含热泪（我也说不清原因）而且常有一股洪流从心中涌上胸口。

My eyes were often full of tears ( I could not tell why) and at times a flood from my heart seemed to pour itself out into my bosom.

youdao