1.his → whose
两句之间没有连词连接,所以把后句变为定语从句.
whose car = the man's car.
2.wrote → writing 或 在wrote前面加上who
原因同上,要么用现在分词短语writing the letter做后置定语修饰the man,要么用who引导的定语从句修饰the man.
3.that → which
定语从句中,关系代词等于先行词all the money(表物),在定语从句中充当介词with的宾语,而且该介宾短语提前至定语从句句首,所以只能用which.