Poll: The battery of medical tests they did ____ very stressful.
The battery of medical tests they did ____ very stressful.
The verb is singular because "battery" is singular. If you said the fifty medical tests they did... then it would be "were" due to fifty being plural. English, what a pain sometimes!
According to subject verb agreement rule that says when the subject is singular the verb must be singular there since battery is singular subject it takes singular verb ( was)