Never before _______ so rapidly developing as it is today.
A. has our country been
B. our country has been
C. has been our country
D. our country hasn‘t been
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Look at this group of people ______ beach volleyball.
A. played
B. is played
C. playing
D. is playing
While _____ the book， he nodded from time to time.
A. reading
B. read
C. is reading
D. is read
He would have given you more help， if he ________ so busy.
A. have not been
B. had not been
C. not have been
D. not had been
Younger children are curious ________ how things workㄛand many of them want to take
A. of
B. about
C. at
D. with
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