Comparisons were drawn between the development of television in the 20th century and the diffusion of printing in the 15th and 16th centuries. Yet much had happened (51) . As was discussed before, it was not until the 19th century that the newspaper became the dominant pre-electronic (52) , following in the wake of the pamphlet and the book and in the company of the periodical. It was during the same time that the communications revolution (53) up, beginning with transport, the railway, and leading on through the telegraph, the telephone, radio, and motion pictures (54) the 20th-century world of the motor car and the air plane. Not everyone sees that process in perspective. It is important to do so.It is generally recognized, (55) , that the introduction of the computer in the early 20th century, followed by the invention of the integrated circuit during the 1960s, radically changed the process, (56) its impact on the media was not immediately (57) . As time went by, computers became smaller and more powerful, and they became "personal" too, as well as (58) , with display becoming sharper and storage (59) increasing. They were thought of, like people, (60) generations, with the distance between generations much smaller. 52().

A. means
B. method
C. medium
D. measure