A．hurtsB．effectsC．showsD．destroys
A. hurts
B. effects
C. shows
D. destroys
One of the differences between cross-sectional research and longitudinal research is that______.
A. the latter usually focuses on only one subject, while the former involves groups of subjects
B. the former can be free from the influence of social changes
C. the latter can be free from the influence of social changes
D. the former costs less money and takes less time
A．neverB．certainlyC．surelyD．probably
A. never
B. certainly
C. surely
D. probably
What was brought to the rich and powerful country when it gained the empire by cutting down its trees to build warships？
A. The country's soil became solid and poor.
B. The country fell into pieces.
C. The country met with floods and famine.
D. All of the above.
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