If you are referring to a period of time before now or a distance, use “past”: “the team performed well in the past,” “the police car drove past the suspect’s house.” If you are referring to the action of passing, however, you need to use “passed“: “when John passed the gravy, he spilled it on his lap,” “the teacher was astonished that none of the students had passed the test.” Remember that no matter however you have ”passed the time” you have never “past the time,” not even in the distant past.

List of errors