TASK DEFINITION: In this task you are given a sentence. You must judge whether the object of the main clause is singular(like: apple) or plural(like: apartments). Label the instances as "Singular" or "Plural" based on your judgment.
PROBLEM: In the common room, the same men were still quietly playing cards.

SOLUTION: Plural

PROBLEM: When we took out a section of the wall, it revealed a spiral staircase leading down to a cellar or dungeon. "

SOLUTION: Singular

PROBLEM: Amy crossed the threshold, shut the door and immediately regretting doing so.

SOLUTION:
Singular