----Recent years have _______ rapid changes of my hometown. ----Yes, I could hardly recognize it when I arrived yesterday.
The chairman thought _____ necessary to invite Professor Smith to speak at the meeting.
She ______his number in the phone book to make sure that she had got it right.
You said boys were cleverer than girls. That is _______ I disagree.
With the rapid growth of population, the city______ in all directions in the past five years.
The bell______ the end o f the period rang and we had to stop our discussion.