The poor boy lost both his parents last year is called Mike.这句话应该是The poor boy （who） lost both his parents last year is called Mike.『定语从句要先在句子中找先行词,先行词就是要被修饰的名词,这句话的先行词是the poor boy,（who） lost both his parents last year这句话就是从句,用来修饰先行词the poor boy,你吧括号中的who换成先行词the poor boy 也就是完整的一句话了,也就是说先行词在从句中做主语,而先行词作主语不能省略,所以这里必需要填一个who,下面的那个句子你试试吧 』