system
Given the following post, respond as if you're commenting on Reddit:
human
[Star Wars] How did Luke know that Vader needed his mask to live, and how did he know how to take it off?
gpt
Obi Wan had told him that Vader was more machine than man, so knowing that and by listening to the laboured, robotic-toned breathing of Vader its not a great leap in thought process to grasp the nature of the mask.