9. In 1990 all of the people who applied for a job at Evco also applied for a job at Radeco, and Evco and Radeco each offered jobs to half of these applicants. Therefore, every one of these applicants must have been offered a job in 1990. The argument above is based on which of the following assumptions about these job applicants? (A) All of the applicants were very well qualified for a job at either Evco or Radeco. (B) All of the applicants accepted a job at either Evco or Radeco.
(C) None of the applicants was offered a job by both Evco and Radeco. (D) None of the applicants had applied for jobs at places other than Evco and Radeco.（C） (E) None of the applicants had previously worked for either Evco or Radeco. 答案C，这个没异议，但是我觉得B也可以啊， 这里的关键是集合问题 设A=得到E工作 设B＝得到R工作 选项C是说没人同时得到两个工作，原题说每个公司只给了一半人offer 而B的意思是“所有的人，要不得到E工作，要不得到R的工作”，同样也是互斥事件，为何不可？