1) I am wearing a sweater and a jacket I am cold. I am wearing a sweater and a jacket; because, I am cold. 2) The old dog is blind it is deaf. The old dog is blind; likewise, it is deaf. 3) Mix all the ingredients put the batter in the oven. Mix all the ingredients; then put the batter in the oven 3) To separate items in a list when commas alone would be confusing.