The old couple have been married for 40 years and never once ___________ with each other.
is no doubt that the Great Wall is one of the wonders of the world.
— Whose Chinese vase is it?— I have no idea, but I’m pretty sure it _______ the old lady.
Mike ________ his car, for he came to work by bus this morning
______ is known to all,the Amber Room belongs to the Russians.
_____ these experiments were successfully completed would we think of going into humans.