LAY ONE'S FINGER ON SOMETHING

finger on something, lay etc one's expr infml I can't lay my finger on the reason for her absence Я не могу понять, почему ее нет I can't put my finger on it Я не пойму, в чем дело I can't quite put my finger on what's wrong with the engine Двигатель барахлит, но я не могу понять, в чем причина