to 后面可接句子吗？

xixiokok

9 {4 b% u, l* F2 T. q: B. ~In order to design policies that aim to change commuting practices it is, however,necessary to have acquired a good understanding of the trips in question and their determinants.  
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这句话里，necessary to 后面为什么可以接 have acquired a ...句子？
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江南一屁

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9 b& v; z# N! F# \3 h& }5 w/ c没有接句子
  }1 q8 A$ F# Vit is necessary to have done sth.
( D  q  x: e( V, j8 [; _: \接了个完成时的动宾结构

. z! _" b! ]; H6 H你可以对比一下下面两句的含义
+ I1 p9 o7 l  C4 N/ S4 mit's necessary to acquire this.
1 V9 L  Z3 m& _1 I! e# t: V有必要（现在或以后）去获取这个
! M% G$ @8 N1 g& X% p8 hit's necessary to have acquired this.
有必要目前已经获取了这个（具有这个是有必要的）
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