1）當(dāng)let后只有一個單音節(jié)動詞，變被動語態(tài)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(bǔ)較長時，let 通常不用被動語態(tài)，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.