It has been necessary to refer repeatedly to the effects of the two world wars in promotin

g all kinds of innovation. It should be【C1】______ also that technological innovations have【C2】______ the character of war itself by the【C3】______ of new mechanical and chemical devices. One weapon developed【C4】______ World War II deserves a special mention. The【C5】______ of rocket propulsion (推进力) was wellknown earlier, and its possibilities as a 【C6】______ of achieving speeds sufficient to escape from the Earth's gravitational (引力的) pull had been【C7】______ out by the Russian and the American scientists. The【C8】______ built an experimental liquid-fuelled rocket in 1926.【C9】______ , a group of German and Romanian pioneers was working across the same lines, and in the 1930s, it was this team that developed a rocket【C10】______ of delivering a warhead hundreds of miles away. Reaching a height of over 100 miles, the V-2 rocket【C11】______ the beginning of the Space Age, and members of its design team were【C12】______ in both the Soviet and United States space programs after the war. Technology had a tremendous social【C13】______ in the period 1900—1945. The automobile and electric power, on the other hand, radically changed both the scale and the quality of 20th-century life,【C14】______ a process of rapid urbanization and a virtual revolution【C15】______ living through mass production of household goods and【C16】______ . The rapid development of the airplane, the cinema,【C17】______ radio made the world seem suddenly smaller and more【C18】______ . The development of many products of the chemical industry further transformed the life of【C19】______ people. In the years following 1945 the constructive and creative opportunities of modern technology could be exploited,【C20】______ the process has not been without its problems.

【C1】

A．observed

B．notified

C．commented

D．detected