Up to Tuesday's attack, the worst school shooting in the U. S. was in March 1998 in Jonesboro,______two boys, aged 11 and 13, shot and killed a teacher and four girls.
In recent years________global warming is becoming ________ concern for people all over the world.
—What made the boy ________ in his classroom? —His hard work and wisdom.
Generally speaking,the limits of a person’s intelligence are fixed at birth,but whether or not he reaches those limits will ________ his environment.
What I should do is ________ the task soon.
Very generally,grammar is ________ with the relations between words in sentences.