分析：1)本句中用了过去完成时的被动语态（been blown down）。过去完成时是一种与过去时相比较而存在的时态，用以表示“过去的过去”的动作或状态。
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现在完成时的被动语态 the present perfect passive voice ; has been kidnapped ; has been done
过去完成时的被动语态 had been done
用现在完成时的被动语态改写下列句子。
Rewrite the following sentences using the present perfect passive voice.
用动词的正确形式将下面的句子变成现在完成时的被动语态。
Change these sentences into the present perfect passive putting the verbs into the correct forms.
用动词的正确形式将下面的句子变成现在完成时的被动语态。
Change these sentences into the Present Perfect Passive, putting the verbs into the correct forms.
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