过去完成时
过去完成时的构成
重要程度：9 分
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<h2>过去完成时的构成</h2>
<p>过去完成时由 "had" 加上动词的过去分词构成。</p>
<ul>
<li>肯定句：主语 + had + 过去分词 + 其他成分</li>
<li>否定句：主语 + had + not (或 hadn't) + 过去分词 + 其他成分</li>
<li>疑问句：Had + 主语 + 过去分词 + 其他成分？</li>
</ul>
<h3>例题说明</h3>
<p>下面是一些例题帮助理解过去完成时的用法：</p>
<ol>
<li><strong>肯定句示例：</strong>By the time I arrived, they had already eaten dinner.</li>
<li><strong>否定句示例：</strong>She hadn't finished her homework before she went to bed.</li>
<li><strong>疑问句示例：</strong>Had you completed the assignment when your teacher asked?</li>
</ol>
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