Subject-verb agreement means that your verb must be conjugated, or changed, to fit (or agree) with the subject. Subjects can be singular or plural. Think of singular and plural as mathematical ...

“Every one of us have a role to play” or “Every one of us has a role to play”? “A bunch of students were waiting outside” or “a bunch of students was waiting outside”? “It is I who am here” or “It is ...