If it were solid carbon, it would be extremely noticeable -- it would be like throwing a 5-pound bag of sugar out the window of your car for every gallon of gas burned.

• 假如，排放的是固体碳，这个结果将会是显而易见的，没燃烧一加仑汽油，就好像是排放出了5磅的面包或者5磅的糖。