Here’s two that get mixed up often…I even get confused on it. Passed is an action, used primarily with people passing by something or another person. Past is used with time.
She passed by him in the past. (if you want to get in your wibbly-wobbly timey-wimey mindset)
Soldier, the white dog, passed by Arwen, the black and white dog, while they raced for the ball.
Time past so slow, each tick on the clock reminding Adrian why she wasn’t out of class–her professor would not stop talking.