Ⅰ.完形填空
Generally，a computer is any device that can perform numerical calculations.__1__，however，the term usually refers to an electronic device that can __2__a series of tasks according to a __3__set of instructions.
In 1953 there were only about 100 computers in use in the __4__world.Today hundreds of millions of computers are being used in homes，schools，businesses，government offices，and universities for almost every __5__purpose.
Modern desktop personal computers，or PCs，are many times more __6__than the huge，milliondollar business computers of the 1960s and 1970s.Most PCs can perform from 400 million to several billion __7__per second.These computers are used not only for household __8__and personal entertainment，but also for most of the automated tasks __9__by small businesses.The fastest desktop computers are called workstations，and they are __10__used for scientific，engineering，or advanced business __11__.
The speed and power of supercomputers，the fa
