【B5】
A. at
B. for
C. on
D. off
The expression "books of about your level of ability..." in the first paragraph is closest
A. the books about your ability
B. the books about your height
C. the books that you could find
D. the books that you can understand
It was from the earliest time ______ men began to study the natural phenomena and heavenly
A. when
B. where
C. that
D. how
Why is sustainable management of tropical forests unlikely to be used in the near future？
A. Because tropical forests contain a majority of animal and plant species on Earth.
Because we have to wait until the experiment in Peru and the U.S. is finished.
C. Because we have no idea about its effect,and if it fails, our planet will be destroyed.
D. Because besides tropical forests,other areas such as the U.S. also have biodiversity.
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