to 后面可接句子吗？

xixiokok

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？

江南一屁

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' z1 o! C! Q" E0 f) D没有接句子
it is necessary to have done sth.
4 H* y2 n  S  B接了个完成时的动宾结构
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. W8 a) D' O7 Q( D' ]你可以对比一下下面两句的含义
it's necessary to acquire this.
0 V0 B) E0 c# ~! ^4 J5 G9 H有必要（现在或以后）去获取这个
! v% l- n' B: m: N1 }it'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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