Modal verbs are often tricky because of how versatile they are, but they are very important because they are used frequently in everyday speech. Whether you want to ask for permission, grant permission, or simply speculate, modal verbs are a handy tool to have when mastering the English language.
What is a Modal Verb?
A modal verb is a verb that expresses ability, permission, probability, necessity, etc. They include can, will, shall, may, etc. In English grammar, verbs can be divided into lexical (normal verbs) and auxiliary verbs, which include modal verbs.
Here is a table of modal verbs and their other variations:
| Can | Could | Be able to |
| Must | Have to | – |
| Will/ Shall | Would | – |
| May | Might | – |
| Should | – | – |
Properties of Modal Verbs
- Modal verbs do not change their form.
Lexical verbs change their form according to the tense they are used in. However, modal verbs remain the same regardless of the tense; i.e. you cannot add a suffix to make the past simple or past participle. It is, however, worth noting that not every modal verb can be used in every tense, and instead, another variation of the verb might be necessary.
- I can speak English and French now, but when I was younger, I could not speak French (NOT I canned not)
- He must do the work soon; he had to do it yesterday (NOT he musted)
- Present Continuous: They can go now (NOT they are canning go now)
- Modal verbs do not require auxiliary verbs.
An auxiliary verb is a verb that adds functional or grammatical meaning to the clause to indicate a tense, modality, voice, etc. As you can see, modal verbs are auxiliary verbs and therefore do not require an extra auxiliary verb to function correctly. Auxiliary verbs include do, be, have, and modal verbs.
For example, the auxiliary verb to do is necessary in present simple and past simple sentences to pose a question or to express a negative. However, modal verbs do not require to do.
- I like cats – I don’t like cats – Do you like cats?
- I can swim – I cannot swim – Can you swim?
In the case where an auxiliary verb is required in the basic structure of the tense, modal verbs may take their other variation, which is NOT also a modal verb. I.E. Can changes to be able to and must changes to have to.
- Present Perfect: I have been able to do the work (NOT I have can do the work)
- Future Simple: I will have to study (NOT I will must study)
2.1. Modal verbs are negated by adding not directly after:
- We should go – We should not go
2.2. Modal verbs are inverted to pose questions:
- They will help – Will they help?
- Most modal verbs can be contracted in their negative form.
Unlike lexical verbs, the negative form of all modal verbs except may and might can be shortened as follows:
| Cannot | Can’t |
| Could not | Couldn’t |
| Will not | Won’t |
| Would not | Wouldn’t |
| Should not | Shouldn’t |
| Shall not | Shan’t |
| Must not | Mustn’t |
Use of Modal Verbs
Ability: can
Can is used to express that we have the ability to do something:
- I can swim, but I can’t fly.
Permission: can, could, may, might
These modal verbs are used to ask for permission; note, however, that the degree of formality and politeness varies:
- Can I use your pen, please? (very informal)
- Could I go to bed, please? (formal/polite)
- May I use the bathroom, please? (formal/polite)
- Might I see your card, please? (very formal/polite)
Obligation: must
Must is used to express an obligation to do something:
- You must be in bed by 10pm.
Possibility: can, could, may, might
These modal verbs are used to talk about the likelihood of something happening:
- It may rain tomorrow, but I am not sure.
- She might be asleep.
- You never know, it could happen.
- That can’t be true.
Requests: can, could, will, would
When making a request, these modal verbs can be used. Similar to modal verbs for permission, modal verbs for requests also vary in their degree of politeness and formality:
- Can you help me? (informal)
- Will you open the door, please? (informal)
- Could you leave a message, please? (formal/polite)
- Would you watch my bag, please? (formal/polite)
Offers: can, shall
Modal verbs can be used to make offers:
- Can we help you?
- Shall I open the door for you?
Advice: should
Should is used to give advice:
- You should take an umbrella in case it rains.
Prediction/Spontaneous decision: will
Will is used to express a prediction based on one’s opinion instead of a fact:
- Manchester United will win the match.
Will is also used when we make a spontaneous decision:
- It’s very hot here. I’ll open the window
This is only the tip of the iceberg. Check out our other articles for more in-depth uses of modal verbs with ‘have’ and modal verbs of probability.