CHECK OUT THIS GREAT WEBSITE TO IMPROVE YOUR ENGLISH
Explore in the above link the blue column on the left . Some labels have few lessons. Others have lots.
I suggest you begin with the "Pronouncing -ed endings" lesson.
You can do the lessons for free BUT JUST ONCE.
This site is now referenced under the label "LESSONS" on the left column of this blog. I called it MAVEN there.
Enjoy and check out the other links as well as the other labels...