题目内容：
根据以下资料，回答题：Comparisons were drawn between the development of television in the 20th century and the diffusion of printing in the15th and l6th centuries．Yet much has happened ___21___. As was discussed before．it was not___22___the l9th century that the newspaper became the dominant preelectronic ___23___，following in me wake of the pamphlet and the book and in the___24___0f the periodical. It was during me same time mat the communications revolution__25__up，beginning with transport，the railways and leading__26__through the telegraph，the telephone，radio and motion pictures__27__the 20th century world of the motor car and the airplane．Not everyone sees that process in __28__．It is important to do so．
It is generally recognized，__29__，that the introduction of the computer in the early 20th century，__30__by the invention of the integrated circuit during the l960s，radically changed the process, __31__its impact on the media was not immediately __32__ .As time went by，computers became smaller and more powerful， and they became personal too, as well as __33__，with display becoming sharper and storage__34__ increasing．They were thought of，like people，__35__generations，with the distance between generations much __36__.
It was within me computer age that the term information society began to be widely used to describe me__37__within which we now live．The communications revolution has__38__both work and leisure and how we think and feel both about place and time，but there have been__39__views about its economic，political，social and cultural implications．Benefits have been weighed __40__harmful outcomes．And generalizations have proved difficult.
A．between
B．before
C．since
D．later
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