The reason for his success is ______ he worked very hard.
I saw some trees the leaves of _____ were black with disease.
We wanted to get home before dark, but it didn't quite as planned.
All that can be eaten _______ eaten up.
—When will you come to see me, Dad? —I will go to see you when you _______ the training course.
—How long _______ at this job? —Since 1990.