问题
单项选择题
By the end of this century, the population of the world ______ , and so may the population of the small country.
A．will be doubled
B．may be double
C．will have to be doubled
D．may have been doubled
答案
参考答案：D
解析：从句子后半部分所用may一词可以确定A、C是不合适的；B中double是形容词，指状态，而不是动态；“也许会翻一番”，也不合适。所以应选may have been doubled。
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