The man who is talking on the phone while drving is reminded by his friend kindly.
the man who talk on the phone while drving 是主语,and his friend 也是主语 is 是谓语 那么warn（提醒） 谁啊?结构就不对.
这样翻译也可以.谷歌：The man was driving with a phone,his friends remind him friendly.