填空题

Begun in the late 1960s by Pentagon weapons researchers as a system for easing
communication between computers in disparate electric networks, the Internet has (1) ______
evolved into a popular vehicle for scientific research, communication, entertainment,
and more. It links together thousands of computer networks such as those belonging (2) ______
to corporations, commercial services, universities, and research centers, joining them as
branches on a tree to larger networks known as backbones. Once a computer is on-line,
that is, connected by modem or networking equipment of the Internet, the user can search (3) ______
through data banks for documents, chat with other computer users, or instant send (4) ______
opinions and observations to the likes of President Bill Clinton, film critic Roger Ebert,
or rocker Billy Idol (just to name a few). No central governing body runs the Internet,
and nobody has an exact census of users. But estimates of the number already range (5) ______
from around 10 million to as high as 5 million. Well over 10,000 separated computer (6) ______
networks are connected by the Internet, and total traffic was expected to double during
1993. Today, the Internet is free resources and commercial services that provide
databases and computer files with a fee. Publishers are seeking to make books and (7) ______
periodicals available on the Internet as a profit-making adventure. Meanwhile, works (8) ______
in the public domain have begun appearing on the Internet for users to "upload" to their (9) ______
computers virtually free of charge. With electronic access to data from all over the
world, scholarly research that in the past would have required months of travel could (10) ______
now be done at one’s desk.