Passage 2
　　In early 1994, when MarkAndreessen was just 23 years old, he arrived in Silicon Valley with an ideathat would change the world. As a student at the University of Illinois, he andhis friends had developed a program called Mosaic, which allowed people toshare information on the worldwide web. Before Mosaic, the web had been usedmainly by scientists and other technical people, who were happy just to sendand receive text. But with Mosaic, Andreessen and his friends had developed aprogram, which could send images over the web as well. Mosaic was an overnightsuccess. It was put on the university’s network at the beginning of 1993. Andby the end of the year, it had over a million users. Soon after, Andreessenwent to seek his fortune in Silicon Valley. Once he got there, he started tohave meetings with a man called Jim Clark, who was one of the Valley’s mostfamous entrepreneurs. In 1994, nobody was making any real money from theInternet, which was still very slow and hard to use.  But Andreessen had seen an opportunity thatwould make him and Clark rich within two years. He suggested they should createa new computer program that would do the same job as Mosaic but would be mucheasier to use. Clark listened carefully to Andreessen, whose ideas andenthusiasm impressed him greatly. Eventually, Clark agreed to invest threemillion dollars of his own money in the project, and to raise an extra fifteenmillion from venture capitalists, who were always keen to listen to Clark’s newideas.
　　Q 19 What do we learn about Mosaic?
　　Q 20 What did Andreessen do upon arriving in Silicon Valley?
　　Q 21Why were venture capitalists willing to join in Clark’sinvestment?