to stop someone from escaping by surrounding and shooting at them if they try to escape

[ often passive ] Government forces were pinned down by resistance fighters 30 miles north of the capital. 政府军被抵抗组织战士钳制在首都以北30英里处。

to make someone provide details about something or make a decision about something

I've tried asking Stephanie, but she's proving difficult to pin down to a particular date. 我已经问过斯蒂芬妮了，可她很难确定具体日期。

to discover exact details about something

We can't pin down where the leak came from. 我们无法确定哪里发生了泄漏。