Monday Mechanics: "ing" words

Ah, the "ing" word: taking, shooting, sleeping…truly any word can be an "ing" word and that's a good thing. If something starts happening while I'm sleeping, I want to know.

When do we need to watch our "ing"? 

When it's accompanied by "was."  So, if I "was sleeping" when something happened and now my sleep's been interrupted, that's fine. But if I was feeling sad and just wanted to go home, then I could be in passive voice. So, "I was feeling sad, so I went home." can become...