Do we know how the Borg adaptation works? I would expect something along the lines of what doesn't kill me makes me stronger. But we see drones being killed and than another drone is immune. How can the Borg even learn what killed the drone if it is killed immediately. What about the viruses, one that created Hugh and co. and the one in Icheb are the Borg now immune? After all id didn't seem so, if they worked twice each. Or does it takes several tries? Also, there should be an limit to the adaptability. After all a ship with an immune drone fight should be one-sided. Please correct me if I am wrong.