56. A词义猜测题。根据They are classified as carcinogens by the International Agency for Research on Cancer. 可知这个词与癌症有关，故可推出carcinogenic意为"致癌的"。
57. C细节题。根据People found the dye in 1883 and gave it the name. Nobody knows the reason, and we cannot give any explanation before we find out.可知还没有人知道"苏丹红"名称的由来。
58. B推断题。根据EU officials have been striving to remove some food products from the shelves. So far 580 products have been recalled.可知某些食品因含有"苏丹红"而被召回。故可推断"苏丹红"经常用作食品添加剂。
