1.
If you try to pin something down , you try to discover exactly what, where, or when it is.
It has taken until now to pin down its exact location...
I can only pin it down to between 1936 and 1942...
If we cannot pin down exactly what we are supposed to be managing, how can we manage it?
PHRASAL VERB : V P n (not pron) , V n P to n , V P wh , also V n P
2.
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.
She couldn’t pin him down to a date...
If you pin people down, they will tell you some puzzling things about stress.
PHRASAL VERB : V n P to/on n , V n P