选词填空.会的来啊.machines ; that; for; in; example; error; either;

选词填空.会的来啊.
machines ; that; for; in; example; error; either; times; which; electronic; mechanical; or; through; than; human
A computer is a machine designed to perform work mathematically and to store and select information that has been fed into it.It is run by [51] mechanical or electronic means.These [52] can do a great deal of complicated work [53] a very short time.A large computer,for [54] ,can add or subtract nine times a second,multiply a thousand [55] a second,or divide five hundred times a second.Its percentage of [56] is about one in a billion digits.It has been estimated [57] human beings making calculations average about one mistake per two hundred digits.The heart of an [58] computer lies in its vacuum tubes,[59] transistors.Its electronic circuits work a thousand times faster [60] the nerve cell in the human brain.A problem that might take a human being two years to solve can be solved by a computer in one minute,but in order to work properly,a computer must be given instructions--it must be programmed.