The trick to looking for subject-verb disagreements is to identify the verb in a single sentence. The verb in the sentence will help you find the subject that will tell you if you have the correct form of the verb. The verb is the easiest to identify as a word that can come right after the pronouns “me”, “you”, “you” and “That”. In cases where two words can match the sentence depending on the pronoun, the verb is the word that changes when you change the temporal form of the sentence. For example, in the sentence “The exhausted runner has crossed the finish line”, both “exhausted” and “crossed” could come after a pronoun. If we change the sentence from the past to the present, “The exhausted runner crosses the finish line”, we see that because “cross” has been modified to put the sentence in the contemporary form, it is the verb. For more information on the precursor-pronoun agreement, please see pages 325-326 of Write for Business and pages 366-367 of Write for Work. . .