问题描述：
求问这句英文的句子结构
A growing number of people have become fully aware that a global ecological crisis is just around the corner if we continue to neglect environmental protection.
主要是have become fully aware是怎么回事,为什么是become而不是became呢,这个到底是什么时态?
A growing number of people have become fully aware that a global ecological crisis is just around the corner if we continue to neglect environmental protection.
主要是have become fully aware是怎么回事,为什么是become而不是became呢,这个到底是什么时态?
问题解答：
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