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: ' They have been concentrating their efforts on building up forces in preparation for D-Day, which didn't happen.

SOLUTION: Plural

PROBLEM: This was somewhat ten times more fun than rolling down the hill.

SOLUTION: Singular

PROBLEM: You have a full balcony.

SOLUTION:
Singular