C．The car­plane may fly as high as normal planes.

　　D．People can park the car­plane in the garage at their home.

　　解析　推理判断题。第六段的第一句提到这款产品设计的起初飞行高度是一万英尺以下，由此可知它不能和正常的飞机飞行同样的高度。

　　答案　C

　　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.

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