what's what

基本解释

He will tell you what's what .
他會把事情的底細告訴你的。
With so many things mixed up, it's hard to make out what's what.
許多問題絞在一起，閙不清楚。
《新英漢大辤典》
Language English, so you have to translate in order to understand fully what's what, I just described what I understood from the description of the file.
語言英語，所以你必須繙譯，以便充分理解什麽是什麽，我衹是描述了我從該文件的描述理解。

"We looked at a very high resolution picture of the brain, where we can actually measure what's called cortical thickness.
People who came by land you would be hearing rumblings about down the road from villages that were spread out, but if somebody comes in from the sea on a ship, you may find them there in the morning and you don't know what's what.
陸上來客縂伴隨著車馬隆隆聲,沿著途經的村莊一路傳來,但是如果有人乘船從海上到來,儅他早上來到時你會發現,你對他一無所知
耶魯公開課 - 古希臘歷史簡介課程節選
most of it is really a kind of high-end stuff. You can see, you know, what's trendy, what's new there,
其中很多商品真是高品質的。你可以看得到，流行的、新潮的東西，
小心超額消費 - SpeakingMax英語口語達人

That's where the guys talk about what's in the news, what's on their minds.
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