to 后面可接句子吗？

xixiokok

$ @, U/ l) ~# ^4 b8 U, AIn 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

& T4 ~0 n; P( h+ Q; C没有接句子
- a3 J$ R. o3 s" U% Zit is necessary to have done sth.
接了个完成时的动宾结构

  \9 m# E6 r1 H" b  F' |你可以对比一下下面两句的含义
it's necessary to acquire this.
有必要（现在或以后）去获取这个
6 J3 j0 M5 J; X& c, _it's necessary to have acquired this.
0 B0 O5 e0 E, E# ?& u) r- `/ }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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