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: But all these actions he had performed mechanically.

SOLUTION: Plural

PROBLEM: If I worked fast enough, adrenaline put up a wall between me and my throbbing headache.

SOLUTION: Singular

PROBLEM: The rider sat very still.

SOLUTION:
Singular