题目

         Watching online open classes U.S. top universities has become indispensable for many young Chinese. Guo Lei, a native of Guangzhou, has become 1       (addict) to various open courses after she watched the online video of Justice: What's the right thing to do. Guo was immediately attracted by the topic and the discussion of the Harvard students about 2      (moral) and justice. About 700 sina micro bloggers 3       (post) different links to the videos. 163.com has launched a special channel for open programs, 4      (provide) more than 1,200 cla（2010?花都区一模）我国科学家已研制出具有自主知识产权的国产计算机芯片-“龙芯一号”和“龙芯二号”，其芯片的核心部件是以高纯硅单质为原料制成的，用化学方法制备高纯硅的反应原理是：SiCl4+2H2Si+4HCl，该反应属于（ ）A．化合反应B．置换反应C．分解反应D．复分解反应