Plumb-Ace advertises that its plumbers are more qualified than plumbers at any other major plumbing firm in the region because Plumb-Ace plumbers must complete a very difficult certification process
Plumb-Ace plumbers may or may not be more qualified, but clearly the certification process is not very difficult, because nearly everyone who takes the written portion of the certification exam passes it very easily
takes for granted that plumbers are not qualified unless they complete some certification process