.

When he was only thirty years old, he had already experienced ___________ most people only experience when they are much older.

    A. what         B. which        C. who           D. when

30. When he was only thirty years old, he had already experienced______most people only experience when they are much older.

     A. what          B. which            C. who        D. When

30. When he was only thirty years old, he had already experienced______most people only experience when they are much older.