Final answer:
Verbs such as 'could' and 'might' are called modal verbs, which are a type of auxiliary verb used to express degrees of certainty, permission, ability, or obligation.
Step-by-step explanation:
Understanding Auxiliary and Modal Verbs
Verbs such as 'could' or 'might' that pair with other verbs to indicate the author's degree of certainty are called modal verbs. These verbs are a subset of auxiliary verbs which assist the main verb and provide additional information about possibilities, obligations, or abilities. An example of this would be the sentence 'I could finish my essay by eight o'clock tonight,' where 'could' is the modal auxiliary and 'finish' is the main verb. It is important to note that 'must' and 'ought to' are also modal auxiliaries and they have no past form. Modal auxiliaries are defined as part of the verb phrase and not as separate adverbs.
In the imperative mood, the subject 'you' is often implied in commands or requests, for example, '(You) Submit your request for time off by Friday.' Here the verb 'submit' is in the imperative mood.
Verb tense consistency is crucial in writing to maintain clarity. Verbs express action or state of being in various tenses to place events in time, and it is important not to accidentally change from past to present tense within a text for no particular reason.