问题详情：
改错：By the time he realizes he walked into a trap, it'll be too late for him to do anything about it.
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【回答】
walked前加has 句意：在他意识到自己已经走进圈套时，对他来说，已无能为力了。根据句意可知用现在完成时。
知识点：现在完成时及其被动式
题型：短文改错
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