Using a proper modal auxiliary: Perhaps he was working for Simons.
【正确答案】正确答案：He may have been working for Simon．
【答案解析】解析：perhaps表示“可能”，可以选用情态助动词may代替。另外时态上可以使用现在完成进行体，表示一种从过去开始一直持续到现在的状态，比较符合句意。