To accomplish that task, follow two occasionally not so simple tasks. Prepositional phrases are one of the main culprits in the misidentification of the true subject of the clause. Among the constitutional rights we cherish is freedom . The group of protesters is blocking the entrance to the building. The annual rituals of the group confuse the neighbors.
Parenthetical phrases can also work to obscure the true subject.
The quiz , as well as all workbook exercises, was collected. QUIZ is the subject. The parenthetical expression does not affect the verb. His jacket , not his shirt or his socks, always seems to match his slacks. It is singular.