The past tense - an aimsir chaite - describes an event which has already happened.
Rules
To put a verbA word used to describe an action or state of being. into the past tense, follow these three rules.
When the verb begins with a consonantA letter representing a speech sound made with the lips, tongue or throat (as opposed to vowels which are made with an open vocal passage)., aspirate / séimhiú In Irish, to aspirate / séimhiú is when the letter 'h' is placed after the first letter in a word. / séimhiú the verb.
When the verb begins with a vowelA letter representing a speech sound made when breath flows freely out of the mouth. The letters a, e, i, o, u are vowels., put a d' before the verb.
When the verb begins with an f, put a d’ before the verb and aspirate / séimhiú the verb.
Remember that you cannot séimhiú / aspirate words that begin with l, n, r and sc, sm, sp, st or vowels.