pin down

基本解释

You must pin down every quotation to its author.
你一定要確定每一條引文的作者是誰。
The teacher cannot pin down the essence of ancient poetry.
老師不能清楚地解釋古代詩歌的實質。
And for almost as long, some of the world’s best diplomatic and legal minds have retorted that trying to pin down a legal definition of aggression is at best fruitless, at worst harmful.
與此同時，一些世界上最傑出的外交家和律師紛紛反駁，他們認爲企圖在法律上明確定義侵略罪，不過徒勞無功之擧，弄不好還貽害無窮。

"It is very difficult to really pin down and there have been these sorts of accusations from the Revolutionary Guards in the past."
That's a quite difficult argument to pin down does it work or does it not work.
這個論証很難確定,是不是說得通。
耶魯公開課 - 死亡課程節選
You need to pin down an object of study, a first principle from which other principles can emerge, and part of the process is to say, "Hey, it's not literature we're talking about.
首要原則是，需要鎖定要談論，即學習的目標，可是，誰知道什麽是文學。
耶魯公開課 - 文學理論導論課程節選

Trading in private shares is growing rapidly, though it's hard to pin down exact numbers.
FORBES: Magazine Article

If you try to pin something down, you try to discover exactly what, where, or when it is.
If you pin someone down, you force them to make a decision or to tell you what their decision is, when they have been trying to avoid doing this.