----I am sorry to have ____ too much of your time.----That's OK, and I am glad to help you.
We couldn’t understand: what could ______ his sudden change of mind?
I didn’t mean to break your vase—it was just ______.
He was breathing ______ after the relay race.
People are concerned about the quality of the air they ______.
She walked home by herself, ______ she knew that it was dangerous.