69. What's the main idea of the passage?     

   A. 17 states are not allowed to set their own emission rules for cars. .

   B. 17 states have the right to set their own standards for emissions.

   C. The proposed California rules are good to help control global warming.

   D. E.P.A.’s decision to deny the proposed California rules, right or wrong.

【解析】B. 从本文第一段就可知文章大意为加州决定采取严厉措施限制引致气温上升及温室效应的

废气排放量，但是被美国环保署否决。