TASK DEFINITION: Generate a topic word for the given sentence. A topic word is usually the name of a person, place, animal, concept or object the sentence is focusing on.
PROBLEM: "if i never see your face again" is the fourth single by maroon 5.

SOLUTION: if i never see your face again

PROBLEM: the alkaline earth metals are the second group of metals on the periodic table.

SOLUTION: alkaline earth metal

PROBLEM: selma blair (b. june 23, 1972) is an american actress.

SOLUTION:
selma blair