Without facts,we cannot form a worthwhile opinion,for we need to have factual knowledge ______ our thinking.
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.
Would it be ______ for you to pick me up at four o’clock and take me to the airport?