Exploring Writing 2nd Edition by John Langan

Exercise 22

In the following passage, there are ten missing commas. Add the commas where needed. The types of mistakes to look for are shown in the box preceding the passage.
2 commas missing between items in a series
1 comma missing after introductory material
4 commas missing around interrupting words
2 commas missing between complete thoughts
1 comma missing with a direct quotation
When I was about ten years old I developed several schemes to avoid eating liver, a food I despise. My first scheme involved my little brother. Timmy too young to realize what a horrible food liver is always ate every bit of his portion. On liver nights, I used to sit next to Tim and slide my slab of meat onto his plate when my parents weren't paying attention. This strategy worked until older and wiser Tim decided to reject his liver along with the rest of us. Another liver-disposal method I used was hiding the meat right on the plate. I'd cut the liver into tiny squares half the size of postage stamps and then I would carefully hide the pieces. I'd put them inside the skin of my baked potato beneath some mashed peas, or under a crumpled paper napkin. This strategy worked perfectly only if my mother didn't look too closely as she scraped the dishes. Once she said to me "Do you know you left a lot of liver on your plate " My best liver trick was to hide the disgusting stuff on a three-inch-wide wooden ledge that ran under our dining-room table. I'd put little pieces of liver on the ledge when Mom wasn't looking; I would sneak the dried-up scraps into the garbage early the next day. Our dog would sometimes smell the liver try to get at it, and bang his head noisily against the bottom of the table. These strategies seemed like a lot of work but I never hesitated to take whatever steps I could. Anything was better than eating a piece of meat that tasted like old socks soaked in mud.