短语动词是一个整体，不可丢掉后面的介词或副词。
This is a photo of the power station that has been set up in my hometown.
My sister will be taken care of by Grandma.
Such a thing has never been heard of before.
let 的用法
1）当let后只有一个单音节动词，变被动语态时，可用不带to 的不定式。
They let the strange go.---> The strange was let go.
2） 若let 后宾补较长时，let 通常不用被动语态，而用allow或permit 代替。
The nurse let me go to see my classmate in the hospital.
----> I was allowed / permitted to see my classmate in the hospital.
