I don't think I know 我不知道啊

Teacher: "John, what is the past participle of the verb to ring?"   John: "What do you think it is, sir?"   Teacher: "I don't think, I KNOW!"   John: "I don't think I know either, sir!"   老师：“John，动词ring的过去分词是什么？”   约翰：“你想它是什么呢？”   老师：“我不用想，我知道！”。   约翰：“我想我也不知道”。