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？

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江南一屁

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6 M( R: U8 K; M, }it is necessary to have done sth.
1 P- @+ b7 c0 R; H9 q( X7 i, X' [接了个完成时的动宾结构
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) h/ H( s" H% j4 U5 G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
3 F6 T5 {# `3 q" oit's necessary to have acquired this.
9 k) }, O1 ^$ d$ ~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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