He is leaving for Australia and it will be three years ________ he comes back.
Professor Smith has written some novels, but he is _____ known for his plays.
How beautifully Mary sings! We have never heard _____ voice.
We must keep our room clean, for dirt and disease go______.
The plans flew smoothly ______ in the sky and people spoke ______ of theexperienced pilots.
Thanks to the good care of the nurses ,the boy is ______ recovering from his lung operation .