—Recent pressure at work may ______ his behavior.
If the weather had been better, we could have had a picnic. But it _____ all day.
I was tired of school work, but my father told me that he didn’t _____school this year.
_____ at his knowledge, all the students showed their respect for their teacher.
He is _____ tearing up what he has written and beginning over again.
The Group of 8(G8) _____ the eight richest countries in the world plays an import part in the international affairs.