The idea is a joint government-manufacturer incentive plan to give consumers with old car trade-ins a $3,000 cash back deal on the purchase of any new car.

VOA: standard.2009.05.18

So I think I can safely say that most people had the right idea and were counting quickly, 3 though I have a feeling that some people who wrote 13 might have forgotten about those 4 f, the 4 f electrons.

我认为我可以放心地说,大部分人的想法都是对的,数得也很快，只是我感觉不少选，13，的人都是因为3,忘了，4，f，4，f，电子。

麻省理工公开课 - 化学原理课程节选