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

没有接句子
& d& A) I' _) \2 a! uit is necessary to have done sth.
3 {0 g' ]9 I9 e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
it's necessary to acquire this.
有必要（现在或以后）去获取这个
it's necessary to have acquired this.
5 U5 d: e9 e. r1 b- m6 b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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