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.  

这句话里，necessary to 后面为什么可以接 have acquired a ...句子？

江南一屁

' b  a% D3 e1 N2 |5 {
没有接句子
: Z$ E- x# U2 Jit is necessary to have done sth.
7 R1 D6 P1 `1 E7 V' ~% ~- T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 l7 r) M! Y. e. {it's necessary to acquire this.
有必要（现在或以后）去获取这个
8 D7 V9 t5 f  c+ uit's necessary to have acquired this.
, Y, I0 [. z( B1 j: m, E. T有必要目前已经获取了这个（具有这个是有必要的）
/ B2 P' ^3 A4 ?* s0 w9 D" H
( B# |# j! c' U/ k$ c0 j* c