51.   They usually would wait until summer school to retake courses or earn credit for extra work.

52.   To earn the credits, he enrolled in summer school at Westark.

53.   Under the Clean Air Act and the Energy Policy Act, large companies can earn pollution credits by doing better than emissions requirements.

54.   Under this strategy, industrial nations could earn credits toward their own emission cuts by paying for reductions in developing countries.

55.   Under a U.S. government program, companies can earn such credits by reducing greenhouse gas emissions lower than required by law.

56.   Under this approach, companies that surpass pollution standards can earn extra credits that they may sell as if they were commodities like soybean futures or stock options.

57.   While they attended high school, they earned college credit by taking demanding classes ranging from art and Latin to calculus and physics.

58.   With one year of football eligibility left, Dixon earned enough credits to enroll at Lambuth.

59.   Canada and Japan have backed the U.S. proposal that countries should be allowed to earn credits against their emissions quotas for the carbon dioxide absorbed by farmlands and forests.

60.   Countries also can earn credit by helping others meet their targets, or by investing in emission-reducing projects in developing countries.