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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没有接句子
$ D& I5 J, [& V" ait is necessary to have done sth.
& P/ t  o3 `+ m6 _2 [  L接了个完成时的动宾结构

你可以对比一下下面两句的含义
0 m- z  N- [) M6 Z- B1 v& yit's necessary to acquire this.
, l5 q% n: y1 Z$ n* X/ G, s2 R有必要（现在或以后）去获取这个
! W* {8 x8 W5 T, Xit'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）