题目内容：
The human beings have polluted the environment seriously．It is time __________the United Nationsmust take some measures．
参考答案：
答案解析：
单选题：The human beings have polluted the environment seriously．It
- 题目分类：2级
- 题目类型：单选题
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The lenient decision of the dean caused anger among the prof
The lenient decision of the dean caused anger among the professors．
That gossip concerning them exploded at length after it had
That gossip concerning them exploded at length after it had been simmering for a
After you，ve started to master the techniques，the real strug
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In some countries，__________is called “equality” does not re
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根据WHO规定，老年人口为
根据WHO规定，老年人口为