Comment by alsothings

I thought you were right for a second, but I'm fairly certain that 'passed' is what I meant. It's the past tense of pass, and thus the correct word. see http://www.grammar-monster.com/easily_confused/past_passed.h... for a good set of examples.

I appreciate that the which/that distinction is tricky, but one is a restrictive clause and the other is not, changing the meaning of the sentence.