I regret _____ you that Tom failed to pass the driving test and that he really regretted ______ your advice on practicing more.
They have to explain ______ us the reason _____ their doing so.
Hand in hand with reading, Dave ____ the habit of making notes.
In the past few years, Chinese scientists ________ great success in the field of space flight.
History is _______ a subject which only lets us know something in history..
I’m ____your class today so you must do ____ I tell you.