Reading Academic Vocabulary Practice Test

Modal auxiliary verbs express modality, such as possibility, when they sit with a main verb. When you say “she might come” or “they could arrive,” the word with the main verb signals that the event is possible rather than certain. This use of modal verbs—can, could, may, might, shall, should, will, would, must and others—is what marks them as expressing possibility or other attitudes toward the action. That’s why this term is the best choice. A general auxiliary verb covers helpers in forming tenses or aspects (like be for continuous forms, have for perfects, or do for questions and emphasis), but it doesn’t inherently convey possibility. A tense marker focuses on time rather than mood, and a linking verb connects the subject to a noun or adjective rather than modifying the main verb to express modality.