SAT scores began dropping in 1963; today, on average, 30% of students do not complete high school in four years, a figure that rises to 50% in poor urban neighborhoods.
SAT 分数从1963年开始下降；今天，平均有30%的学生没有在四年内完成高中学业，这一数字在贫穷的城市社区达到了50%。
2
Computer scientists have created an animated figure called Betty's Brain, who has been "taught" about environmental science by hundreds of middle school students
计算机科学家创造了一个名为“贝蒂的大脑”的动画形象，它已向数百名中学生“教授”了环境科学知识。
3
Computer scientists have created an animated figure called Betty's Brain, who has been "taught" about environmental science by hundreds of middle school students.