This kind of paper was as soft and light as silk but ______ expensive.
--I'm told that John had another car accident this morning. --I believe not. He _________so careless.
The Bunsen Burner is so named because it is thought ___________ by Robert Bunsen.
-I didn't know this was a one-way street, officer.
--Which play shall we go and see?
You _________think you're clever, but that doesn't give you the right to order me about!