题目内容

在光合作用实验里，如果所用的水中有0．44%的水分子含18О，二氧化碳中有0．68%的二氧化碳分子含18О。那么，植物进行光合作用释放的氧气中，含18О的比例为-----（     ）
A．0．20%B．0．44%C．0．68%D．0．88%
B解析:
略
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