题目内容
8、The Amazon Valley is very important to the natural balance of the earth. Forty percent of the world’s oxygen ______ there.
A. produces B. is produced C. has produced D. has been produced
试题答案
8、B
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A. produces B. is produced C. has produced D. has been produced
查看习题详情和答案>>The Amazon valley is very important to the natural balance of the earth．Forty percent of the world’s oxygen there．
A．produces B．has produced C．is produced D．has been produced
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