Why wouldn't "The years pass and certain things change" be acceptable?
I'm pretty sure it was accepted in a previous lesson. Needs to be reported.
Why is it "gli anni" and not "I anni"
Consider the article "gli" as the plural of the article lo and its truncated form l'. It's "l'anno" in the singular, so "gli anni" in the plural.
When you have a vowel in the next word and it's plural, you use gli instead of i. ex: gli uomini, gli ombrelli