TASK DEFINITION: In this task you are given a sentence. You must judge whether subject of the main clause is singular or plural. Label the instances as "Singular" or "Plural" based on your judgment.
PROBLEM: Despair might be the tune he sang to himself about what he did, but a deep polished vanity lay beneath it.

SOLUTION: Singular

PROBLEM: Bare floors, blank walls, all painted the same shade of off-white.

SOLUTION: Plural

PROBLEM: The marine layer was far off the coast, giving the sun the opportunity to shine and the temperature to reach the high seventies.

SOLUTION:
Singular