单选题 The marvel of the machine age, the electronic computer has been 1 only since 1946. It can do simple computations—add, subtract, multiply and divide— 2 lighting speed and perfect accuracy. It can multiply two 1-digit number in 1/1,1000 seconds, a problem that would 3 an average person five minutes to do with pencil and paper. Some computers can work 500,000 times faster than 4 .
Once it is given a "program"—that is, a 5 set of instructions devised by a technician trained in computer language—a computer can gather 6 information for many purposes. For example, it can 7 bank accounts up to date and make out electric bills. If you are planning a trip by plane, the computer will find out 8 route to take. Not only can the computer gather facts, it can also store them as fast as they are gathered and can 9 whenever they are needed. 10 gathering and storing information, the computer can also solve complicated problems that once took months for people to do.
For example, 11 sixteen hours an electronic brain solved a difficult design problem. First, it was 12 all the information necessary for designing a chemical plant. After running through 16,000 possible designs, it 13 the plan for the plant that would produce the most chemical at the lowest cost. Then it issued a printed set of exact 14 . Before it solved this problem, a team of engineers having the same information had worked for a year to produce only three designs, 15 of which was as efficient as the computer"s.