Thanks to scientific research, we now have a good understanding of ______ an earthquake is and why it happens.
September 30 is the day_______which you must pay your bill.
I think Mrs. Stark could bebetween 50 and 60 years of age.
Raymond's parents wanted him to havepossible education.
______the nurses want a pay increase, they want reduced hours as well.
—Who’s that at the door?— is the milkman.