1）當let后只有一個單音節動詞，變被動語態時，可用不帶to 的不定式。
They let the strange go.---> The strange was let go.
2） 若let 后賓補較長時，let 通常不用被動語態，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.
