The two things are the same in outward form but different________.
Smoking, ______ is a bad habit, is popular with the young.
The number of the people who own cars ______since 1990.
— Is he coming? — ______. He may not have time.
It took him a long time to ______ the skills he needed to become an artist.
There is no doubt ______ he did is good for us.