I have a problem with these sentences. which one is correct?and why?
- He studied the role of an/the/ ' extended family in caring for older people.
I have a problem with these sentences. which one is correct?and why?
The choice depends on what meaning you are trying to convey.
He studied the role of an extended family in caring for older people.
This implies that he studied a particular extended family and how it affected the care of the older people in that "family".
He studied the role of the extended family in caring for older people.
This implies that he studied multiple extended families and collected/correlated his observations into some sort of organized work.
He studied the role of extended family in caring for older people.
This is similar to the "the" case except that the implication is that he studied the concept of "extended family".
(Though it should be noted that the above is just "implications" -- you'd have to read the final report to know if these were on target or not.)