The subject-verb agreement is tricky in a sentence or dependent clause that begins with the words "there, that, which, who," or "what" because they are not real subjects to determine agreement. You ...

Like the subject, the object is usually a noun (‘the piano’) or a noun phrase, (‘the big, black piano’). Verbs that take objects describe some kind of action rather than a state of being.

Subject pronouns are used to replace a noun which is the subject of the verb, in other words, the person or thing that is doing the action in the sentence.