to 后面可接句子吗？

xixiokok

* d0 C+ c4 n6 t# `+ J2 m6 mIn 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.  
. ~3 B* k9 h/ |$ ?5 s
; r0 i/ N' t& N$ E0 B这句话里，necessary to 后面为什么可以接 have acquired a ...句子？
6 l5 e, F1 F( ~8 r) z
# O. B+ B, L$ S& o+ G" `

江南一屁

  D' G8 P% v$ W
. p: |" P6 ^5 v7 x没有接句子
it is necessary to have done sth.
7 x2 U7 K4 O. C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
/ P, |  a8 q. l8 [! \: R" B! Yit's necessary to have acquired this.
* e4 k4 o+ o- J# W1 S有必要目前已经获取了这个（具有这个是有必要的）


/ E4 M1 _# I/ Q( @3 H