The school has developed an online system________ students can choose their own teachers.
He glanced out of the window,______ that the post office was still closed.
Her mother does not ______ of her going to study in the United States alone.
—Are train services now back to ______after last week's snowstorm? —Yes,they are.
He told this to somebody else,not realizing that he ______.
______ admitted to famous universities,parents should try to cure their children ______ bad habits.