Final answer:
The subject of a sentence is the noun or pronoun that performs the action or is being described. In this question, all the options except for 'Before we begin' represent subjects.
Step-by-step explanation:
The subject of a sentence is the noun or pronoun that performs the action or is being described. It is usually the main focus of the sentence. In this question, all the options except for Before we begin represent subjects. 'Before we begin' is a prepositional phrase and not a subject.
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