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: Then the vigil began.

SOLUTION: Singular

PROBLEM: The man-made chemical polonium leaks from the engines by tiny droplets.

SOLUTION: Singular

PROBLEM: In the absence of any other diversion, cricket was all they had to fill up the hours between shifts.

SOLUTION:
Singular