3.3 A common error

Modals, or modal auxiliary verbs, such as may, might, could, should, and must are used before the infinitives of other verbs to add meaning connected with certainty or obligation or freedom to act.  Modals are not usually used to say (a) that something definitely exists or (b) definitely happened.  We use them to talk about things which we expect, which are not possible, which we want to happen, which we are not sure about, or which we think are necessary. 

• Modals have no ‘s’ in the third person singular

  He might wear his uniform today. (NOT He might wears his uniform today)

•  After modals, we use the base form of verbs.

  You must do your homework (NOT You must to do your homework)

• Progressive, perfect, and passive forms are also possible.

  He must be working very hard.

  She shouldn’t have copied that homework assignment.

  Graded work cannot be written at home.

•  Maybe’ should not be confused with ‘may be’.  Although similar in meaning, maybe is an adverb, and may be is a modal followed by the base form of the verb be.

  Maybe she is upstairs

  She may be upstairs.

In addition, in argumentative essays, modals can be used to control the tone of your ideas.  For example, words such as must and should show a reader what your opinion on a matter is.  On the other hand, words such as can, could, may, might, and would can be used to avoid making sweeping statements or to make an opposing opinion sound weaker.

While some people may say that uniforms don’t help them get better grades, the evidence clearly shows that schools must enforce a strict uniform policy.