[单项选择]　　Passage 2 　　Questions 6 to 10 are based on the following passage： 　　（77） Much unfriendly feeling towards computers has been based on the fear of widespread unemployment resulting from their introduction. Computers are often used as part of automated （自动化） production systems requiring a least possible number of operators， causing the loss of many jobs. This has happened， for example， in many steelworks. 　　On the other hand， computers do create jobs. They are more skilled and better paid， though fewer in number than those they replace. Many activities could not continue in their present formwithout computers， no matter how many people are employed. Examples are the check clearing （交换） system of major banks and the weather forecasting system. 　　When a firm introduces computers， a few people are usually employed in key posts （such as jobs of operations managers） while other staff are re-trained as operators， programmers， and data preparation staff. （78） After the new system h
A. the possible widespread unemployment caused by their introduction
B. their use as part of automated production systems
C. the least possible number of operators
D. the production system in steelworks