C
A 33yearold financial analyst in California recently quit his job to devote himself to an unpaid job teaching math on the Internet，and his lessons are reaching almost 100,000 people a month.Salman Khan's voice is heard every day on the Net-by tens of thousands of students around the world who are hungry for help learning math.He has posted 1,200 lessons on YouTube that appear on an electronic blackboard，which range from basic addition to advanced mathematics for science and finance.And they are free.
Khan lives in Silicon Valley，with his wife，a doctor，and their new baby.He got the idea for his“Khan Academy” four years ago，when he taught a young cousin how to convert kilograms to grams.With Khan's help，the cousin got good at math，and Khan began a new career.
Now，Khan records his lessons himself，but he never goes on camera.“It feels like my voice in their head.You're looking at it and it feels like someone's over your shoulder talking in your ear，as opposed to someone at the blackboard，which is distant from you，”he said.
When Springfield High School in Palo Alto，California invited Khan to speak in person-he immediately connected to the students there.
The idea of short lessons that can be played over and over again attracted high school senior Bridget Meaney.She said she had trouble with math in the seventh grade.“I think the teachers are good，but they can't teach at a speed that's perfect for everyone，”she said.“I like the idea of learning something in class but then going back and pressing pause or rewind and actually getting a deeper understanding of it.”
Originally，Khan kept his lessons short because of YouTube restrictions.Now，he thinks short_is_better.“Education researchers now tell me that 10 minutes is how long someone can have a high level of concentration.And anything beyond that and your brain switches off，”he said.
For Khan，teaching math，science，and finance is just the beginning.He says he's ready to expand his YouTube site to include other subjects as well.
【语篇解读】 加利福尼亚一个财务分析师放弃自己的工作，而从事一个没有报酬的工作——在网络上教授数学，结果很受欢迎……
43.What gave Khan the idea of teaching math online?
A.His success in helping his cousin learn math.
B.His discovery that many students found learning math difficult.
C.A suggestion made to him at a local high school.
D.His interest in Internet teaching.
解析 细节理解题。根据第二段最后两句可知，A项正确，即他的这个想法源于他辅导自己堂弟数学，并使他的数学成绩提高之后。
答案 A
44.Why does Khan never go on camera?
A.He's too shy to show his face on camera.
B.It's restricted by YouTube for education videos.
C.He wants to keep distance from the viewers.
D.He wants to create a more relaxing learning atmosphere.
解析 推理判断题。由第三段Khan说的话可推知，Khan不上镜是想给学生提供一个更宽松的学习环境。故选D。
答案 D
45.From the passage，we know that________.
A.Khan travels to many schools to promote his lessons
B.Khan plans to include more subjects in the future
C.Khan gives live math lessons every day for free
D.Khan sets up the“Khan Academy”with his wife
解析 细节理解题。根据文章最后一句话“He says he's ready to expand his YouTube site to include other subjects as well”可直接得到答案。
答案 B
46.Why does Bridget Meaney like Khan's lessons?
A.Khan teaches seventh grade math better than her teacher.
B.The lessons can be watched repeatedly until fully understood.
C.She can perfectly follow the pace of Khan's teaching.
D.She cannot concentrate when learning in class.
解析 推理判断题。根据倒数第三段第一句话和该段最后一句话可知，她之所以喜欢Khan的课，是因为这个课程可以重复听，直到最后完全懂了为止。因此B项正确。
答案 B
