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？
, a0 Y" ?; N: y- k

江南一屁

' B: ~) W. A' c没有接句子
it is necessary to have done sth.
5 L  a! v4 e. u# K/ w; |. R接了个完成时的动宾结构
4 {) Q0 B: S5 F  w
& l: M% {# O2 [" L! V0 l你可以对比一下下面两句的含义
, v8 x; V) M5 G0 e: C- wit'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.
有必要目前已经获取了这个（具有这个是有必要的）
# p! w8 {8 ^1 x
, W% S! U' m& p% X- E2 ?