请问这个句子的to 什么语法成分?
Her show now has a hard political edge to it.她现在的表现具有强烈的政治性.【这是字典的句子,没有上下文.】
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再加个问题：He was so much on edge thinking about Dr.MacDonald that he hadn't realized he was driving so fast.
为什么that从句用过去完成时？