读不懂这个题干， 请指教： 206. A significant number of complex repair jobs carried out by Ace Repairshave to be reworked under the company's warranty. The reworked jobs are invariably satisfactory. When initial repairs are indequate, therefore , it is not because the mechanics lack competence: rather , there is clearly a level of focused concerntration that complex repairs require that is elicited more reliably by rework jobs than first-time jobs. The argument above assumes which of the following? A. There is no systematic difference in membership between the group of mechanics who do first-time jobs and the group of those who do rework jobs. B. there is no company that successfully competes with Ace Repairs for complex repair jobs. C. Ace Repairs' warranty is good on fist-time jobs but does not cover rework jobs D. Ace Repairs does not in any way penalize mechanics who have worked won complex repair jobs that later had to be reworked E. There is no category of repair jobs in which Ace Repairs inviably carries out fist-time jobs satisfactory. 答案是A 不明白绿色部分的提干是什么意思，请指教！ | 
