_____ all the animals I’ve ever had, these two dogs are the most sensitive to the spoken word.
People have heard _______ the President has said; they are waiting to see _______ he will do.
______ we are doing has never been done before.
_______ she couldn’t understand was ______ fewer and fewer students showed interest in her lessons.
It is pretty well understood _______ controls the flow of carbon dioxide in and out the atmosphere today.
Country life gives him peace and quiet, which is ______ he can’t enjoy while living in big cities.