I used to quarrel a lot with my parents, but now we_______ fine.
Is this the research center _____you visited the lab last year ?
Don’t believe him .He is just _____ an excuse .
-Would you mind if I take the seat? - .
The bell rang and came in Mr.Brown, a book in his hand. Then the class began.
In the past 5 years a great deal of money _____ improving the environment of the school.