gwd-7-27

A significant number of complex repair jobs carried out by Ace Repair have to be reworked under the company's warranty. The reworked jobs are invariablly satisfactory. When initial repairs are inadequate, therefore, it is not because of 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 by 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.

E. There is no category of repair jobs in which Ace Repairs invarialy carries out first-time jobs satisfactorily.

压根就看不懂题干．．．