Pronouncing -ED (Linguaspectrum)
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The important thing that you must remember is that in the past ending -ED, the letter E is not pronounced (except when the verb ends in T or D, when it sounds /ɪd/).

But if you (or your teacher) want to be more precise, this video will show you how to pronounce the ending letter D /t/ or /d/ depending on the last sound of the verb.