80. A report by the American Academy for the Advancement of Science has concluded that much of the current uncontrolled dioxins to which North Americans are exposed comes from the incineration wastes. 正确答案 (E)many of the currently uncontrolled dioxins to which North Americans are exposed come 谁能帮我回答一下,这里为什么要用to which? 它指定是什么?
dioxins which North Americans are exposed to comes from the incineration wastes. 等于 dioxins to which North Americans are exposed comes from the incineration wastes. which是修饰dioxins