He is quite worn out from years of hard work. He is not the man ______ he was twenty years ago.
 
【正确答案】 B
【答案解析】 定语从句。这里the man并不表示某个人,而是强调某个状态、属性或身份,所以不用C或D。that在从句中做表语,which做表语时一般引导非限制性从句,这时不能用that代替,故答案为B。