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: Unseen to him, their pursuers followed.

SOLUTION: Plural

PROBLEM: Just a strip of tarmac lined either side by overhanging trees.

SOLUTION: Singular

PROBLEM: The wolves growled and howled with rage as they retreated and disappeared into the trees that were now above them.

SOLUTION:
Plural