U2_W-P 大学体验英语 4册.ppt

* Return to Menu General Writing Practical Writing When describing functions or uses of something, first of all you tell the reader what it can do or can perform. Then you also need to indicate where it is used or who will use it. Now read the following examples. Describing Functions and Uses What functions can be performed? The computer is a machine that performs tasks, such as mathematical calculations or electronic communication, under the control of a set of instructions called a program. Programs usually reside within the computer and are retrieved and processed by the computer’s electronics, and the program results are stored or routed to output devices, such as video display monitors or printers. Computers are used to perform a wide variety of activities with reliability, accuracy, and speed. Describing Functions and Uses Where is it used? People use computers in a wide variety of ways. In business, computers track inventories with bar codes and scanners, check the credit status of customers, and transfer funds electronically. In homes, tiny computers embedded in the electronic circuitry of most appliances control the indoor temperature, operate home security systems, tell the time, and turn videocassette recorders on and off. Computers in automobiles regulate the flow of fuel, thereby increasing gas mileage. Computers also entertain, creating digitized sound on stereo systems or computer-animated features from a digitally encoded laser disc. Describing Functions and Uses Exercises Computer programs, or applications, exist to aid every level of education, from programs that teach simple addition or sentence construction to programs that teach advanced calculus. Educators use computers to track grades and prepare notes; with computer-controlled projection units, they can add graphics, sound, and animation to their lectures. Computers are used extensively in scientific research to solve mathematical problems, display complicated data, or model systems that ar