同学，你好。这道题目之前也已经给你解释过了，这句话的原话应该是： Peter was concerned about his own safety,Peter put a card on the back of his car reading"Caution---Newly Licensed." 这里为了句子更加简练，用动词的过去分词作状语，所以省略了Peter was。concerned前面不用添加任何成分。