Use helping (auxiliary) verbs with a base form, present participle, or past participle to form verb tenses, questions, and negatives. The most common helping verbs are forms of be, do, and have.

We have considered all viewpoints.

The problem is ranking them fairly.

Do you know the answer? No, I do not know it.

A special set of helping verbs known as auxiliaries—can, could, might, may, must, ought to, shall, will, should, would—indicate future actions, possibility, necessity, obligation, and so on.

You can see three states from the top of the mountain.

She should visit this spot more often.