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.来源:和谐
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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.