题目内容：
Without most people realizing it, there has been a revolution in office work over the last ten years. Before that time, large computers were only used by large, rich companies that could afford the investment. With the advancement of technology, small computers have come onto the market which are capable of doing the work which used to be done by much larger and more expensive computers, so now most smaller companies can use them. The main development in small computers has been in the field of word processors, or WP's as they are often calleD．40% of British offices are now estimated to have a word processor for both secretary and manager. The secretary is freed from a lot of routine work, such as re-typing letters and storing papers. He or she can use this time to do other more interesting work for the boss. From a manager's point of view, secretarial time is being made better use of and money can be saved by doing routine jobs automatically outside office hours.
But is it all good? If a lot of routine secretarial work can be done automati?cally , surely this will mean that fewer secretaries will be needeD．Another worry is the increasing medical problems related to work with visual display units. The case of a slow loss of sight among people using word processors seems to have risen greatly. It is also feared that if a woman works at a VDU for long hours, the unborn child in her body might be killeD．Safety screens to put over a VDU have been invented but few companies in England bother to buy them.
Whatever the arguments for or against word processors, they are a key feature of this revolution in office practice.
回答问题
Ten years ago, smaller companies did not use large computers because_______. A．these companies had not enough money to buy such expensive computers
B．these computers could not do the work that small computers can do today
C．these computers did not come onto the market
D．these companies did not need to use this new technology
参考答案：
答案解析：