阅读下面短文，从A、B、C、D四个选项中选出最佳选项，使短文完整、通顺。
He has millions of students from all over the world. They listen to his classes online. They ____16____ see his face on the screen. Salman Khan, 42, from the US, is the founder（创始人）of the learning website Khan Academy.
Unlike other online courses that film teachers ____17____ classes, Khan's videos only use his voice and a digital blackboard for writing. He says he doesn't want a human face to distract（使分心）students. Khan also makes his classes ____18____ 10 to 15 minutes so that students won't lose interest. They can also get scores from taking classes.
The courses are translated into more than 36 different languages ____19____ Chinese. About 80 teachers from the world's top universities are now also teaching on the website. But all this started nine years ago with just one man-Khan. These kinds of special courses make Khan Academy one of the world's ____20____ online education websites.
In 2006, Khan made homemade videos to help his ____21____ grade cousin with math. He posted the videos online and got thousands of views. This encouraged him to make more videos and create his own website Khan Academy.
Khan understands that many kids, especially those in developing countries, cannot get a good education. He has three degrees from universities. He wants to use his ____22____ to help more people. Thus, his courses are all offered for free. "Our task is to ____23____ a free, world-class education for anyone, anywhere," he said.
Khan's website has ____24____ become very popular worldwide but won a lot of respect（尊重）. Even Bill Gates, the founder of Micros of, is one of his fans. Gates _____25_____ over $1.5 million to support Khan and named him "the teacher to the world".
16. A. always B. usually C. never D. sometimes
17. A. to give B. giving C. give D. gave
18. A. as long as B. as much as C. as short as D. as soon as
19. A. including B. with C. as D. beside
20. A. least popular B. more popular C. popular D. most popular
21. A. nine B. nineth C. ninth D. the ninth
22. A. knowledge B. fame C. courage D. value
23. A. give B. offer C. provide D. pay
24. A. ever B. already C. not D. not only
25. A. gave out B. gave off C. gave up D. gave away
这是一篇记叙文，文章主要讲述可汗在网站上只使用他的声音和一个电子黑板来写字，发只有10到15分钟那么短的视频来教学。这些视频被翻译成各种语言，他的学生遍及世界各地，使得可汗学院成为世界上最受欢迎的在线教育网站之一。他用他的知识来帮助更多的人，使得他的网站受欢迎，而且赢得了很多尊重。