其中之一是教育因素：大学毕业生过去和现在都比只念过中学的工人收人要高，而中学毕业生比没有念完中学的工人挣钱要多。

• One of those is education: college graduates have earned and are still earning more than workers who have only finished high school,and high-school graduates earn more than workers who didn't complete their studies there.