A new study finds that the average performance of students from the lowest income families in the US lags （滞后）about three to four years behind that of the highest income students一an achievement gap that has remained constant for decades. An analysis of standardized tests given to more than 2. 7 million middle and high school students over 40 years suggests that federal education programs aimed at closing the gap are falling short.
Researchers looked at results from four different programs conducted nationwide at various intervals from 1971 to 2015 to test teenagers in math, reading and science. A total of 98 exams were used in the programs, testing students aged 13-15 as well as 17-year-olds. Test scores for 17-year-old students in the bottom 10th income percentile （百分位）were far lower than those in the top 10th percentile.
Meanwhile, the overall test scores didn't shift for 17-year-olds during the study period.
They did improve slightly for 13- to 15-year-olds, which suggests that federal programs for younger students have been helpful. But the lowest income students still score much lower than the highest income students. **Programs for older students are badly needed," says study coauthor Eric Hanushek. an education economist at Stanford University. "Lower achievement in high school leads to lower earning potential throughout adulthood. The next generation is going to look a lot like this generation. Kids from poor families will become poor themselves."
Whether the problem is worsening, however, is up for debate. A 2011 study, conducted by Stanford education sociologist Sean Reardon, looked at 12 exams administered from 1960 to 2007, and found that the gap in test scores between the poorest and the wealthiest students grew by 40 percent. It shows the poorest students lag about three to six years behind their wealthier peers in learning. Reardon suggested parents of means were increasingly investing in their children's education, sharpening the divide.
The different results between the new study and that conducted in 2011 come down to the fact that the researchers analyzed results from different tests and how they categorized （分类） family income level, says education sociologist Anna Chmielewski. Hanushek and Reardon agree that the income-related achievement gap is alarming.
28. What does the result of the new study indicate?
A. The poorest students' lagging behind exists in specific age groups.
B. A better standard for category should be adopted in the study.
C. The federal education programs turned out unsuccessful generally.
D. A better school performance necessarily leads to higher income.
29. How does the author present the serious issue?
A. By showing the discussion result. B. By clarifying some points.
C. By doing a questionnaire. D. By making a comparison.
30. What may cause the different results of the two studies?
A. The different countries. B. The analytical methods.
C. The income assessments. D. The different ranges of age.
31. Why does the income-related achievement gap concern people?
A. It will disappear eventually.
B. It will further widen the social gap.
C. It results in the students blind competitions.
D. It makes Americans smarter and richer.

28. C推断题。根据第1段最后一句可推知.联邦教育项目没有达到目的。
29. D推断题。通读最后两段可推知，文章至零迪以平琴归理鲫容的早零亲该哩申摩咚△琶年欧哩学告板敏 咨丁严申I呵攀。
30. C站带赢 根据最后一段第1句可知.Anna Chmielewski认为,造成这两项研究结果不同的原因是他们对 家庭收入情况进行划分的方式不同。
31. B推断题。根据第3段和文章最后一句可知.研究人员认为.孩子们的成绩差距会进一步加大他们的社会 差距,这个问题令人担忧。