to be pinned down by sth【军】被…困住；被…压(制)住
A section was pinned down by heavy enemy fire.小分队被敌人猛烈的火力压制住了。
2.(force to be specific)to pin sb down or to pin down sb迫使…作决定；迫使…详述；迫使…信守承诺
If you pin people down, they will tell you something puzzling about stress.如果非让他们说的话, 人们会告诉你有关压力的令人费解之事。
3.(define clearly)to pin sth down or to pin down sth明确；说清楚；弄清楚
I can only pin it down to between 1936 and 1942.我只能确定是在1936年至1942年期间。
It has taken until now to pin down its exact location.直到现在才搞清楚它的准确位置。