问题描述:
We should think about what we can do ____________ (keep) animals and plants from becoming endangered.
用所给动词的适当形式填空.答案是to keep,我想知道为什么加to啊?
用所给动词的适当形式填空.答案是to keep,我想知道为什么加to啊?
问题解答:
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