Agroup of words with a subject and verb that does not express a complete thought is called a(n) .

That would be called a Subordinate Clause.

dependent clause  

Explanation :

A group of words with a subject and verb that does not express a complete thought is called a(n) dependent clause.

2b2t

explanation:

2b2t

every person should make it a priority to serve at least two hours per week.

it's an extremely important civic responsibility that is invaluable to citizens most in need is the correct one