ph.

1. 确定；证实
If you try to pin something down, you try to discover exactly what, where, or when it is.

2. 迫使…作出决定（或明确表态）
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.

1. define clearly

e.g. I cannot narrow down the rules for this game

Synonym: peg downnail downnarrow downnarrowspecify

2. attach with or as if with a pin

e.g. pin up a picture

Synonym: pin up

3. place in a confining or embarrassing position

e.g. He was trapped in a difficult situation

Synonym: trap