-is restricted
(In the U.S. the proportion of income spent on 'display' goods has
increased since 1985 VS Our society has become very materialistic.)
-is unified
(All the speeches that people make at AA meeting are confessional.
VS All the speakers at the AA speak about themselves, and the meetings
never last more than an hour.)
-is specific
(Drug addiction has caused a huge increase in property crimes. VS
Drug addiction is a big problem)