They are used as auxiliaries to the present and past perfect tenses.

它们是用作现在完成时和过去完成时的助动词。

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The present and past perfect tenses both belong to the perfect tense.

现在完成时和过去完成时都属于完成时态。

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The present and past perfect tenses both belong to the perfect tense.

现在完成时和过去完成时都属于完成时态。

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