(C)A computer is a machine with a complex network of electronic circuits ( 电路) that operate switches. The switches are capable of being in one of two possible states, that is, on or off. The machine is capable of storing and dealing with numbers, letters, and characters. The basic idea of a computer is that we can make the machine do what we want simply by inputting signals that turn certain switches on and turn others off.Computers are thought to have many remarkable powers. However, most computers, whether large or small, have three basic capabilities. First, computers have circuits for performing arithmetic operations, such as: addition, subtraction, division, multiplication and exponentiation. Second, computers have a means of communicating with the user. After all, if we couldn't feed information in and get results back, these machines wouldn't be of much use. However, certain computers (commonly minicomputers and microcomputers) are used to control directly things such as robots (机器人), medical instruments, etc.Some of the most common methods of inputting information are to use magnetic tape, disks, and terminals. The computer's input device reads the information into the computer.For outputting information, two common devices used are a printer which prints the new information on paper, or a CRT display screen which shows the results on a TV-like screen.Third, computers have circuits which can make decisions. The kinds of decisions which computer circuits can make are not of the type: 'Who would win a war between two countries?' or 'Who is the richest person in the world?' Unfortunately, the computer can only decide three things, namely: Is one number less than another? Axe two numbers equal? and, Is one number greater than another?1、 A computer is, in a sense, simple in that it ______.A.consists only of electronic circuitsB.can only store and deal with numbers, letters, and charactersC.performs its functions by means of operating switchesD.cannot work without signals2、 A computer can NOT ______.E.perform arithmetic operationsmunicate with the userG.make a certain kind of decisionH.be of much use without input and output3、 In the second paragraph, "remarkable powers" means ______.I.extraordinary functionsJ.great strengthK.talkative charactersL.abilities to give marks4、 It seems unfortunate that basically a computer can ______.M.not be of much useN.only compare two numbersO.be used only by expertsP.perform a limited number of functions5、 The best possible title of the passage is ______.puter and its usersputer and its structureputer and its futureputer and its basic capabilities