Please, correct my sentences bellow. :)
1. Valentine’s day, February 14, is a special holiday for sweethearts.
2. At long last, the chief executive officer, has decided to step down.
3. Tonight’s dupper, leftovers from last night, did not taste any better tonight than last night.
4. The only entrance to the closet, the door was kept locked at all times.
5. In the cold of winter, a wall heating unit, would not turn on.
6. The new tile pattern, yellow flowers on a while background, really brightens up the room.
7. The high-powered computer the most powerful machine of its type, was finally readied for use.
8. A longtime friend and confidant, the psychologist was often invited over for Sunday dinner.