All About Modal Verbs in English

General Introduction: What Do We Mean by Modal Verbs?

According to many grammar books, modal auxiliary verbs (also can be called modal auxiliaries or modals) are irregular verbs that are completely different from normal verbs we use for our daily activities, like “eat”, “walk”, “drive” etc…

The list of modal verbs in English language is limited, but their functionalities in the language are numerous and sometimes can be confusing.

As its name may suggest, a modal auxiliary refers to the helping nature of its function with the verb that always follows it. In this lesson, we are going to discuss the wide range of communicative functions of modal verbs.

Different Communicative Functions of Modal verbs

Modal verbs refer to many communicative functions. Here is a comprehensive list of these functions:

Ability	التعبير عن القدرة على فعل شيء ما
Permission	التعبير عن الإذن بفعل شيء ما
Obligation	الوجوب أو الإجبار على فعل شيء ما
Advice	تقديم النصيحة
Possibility / capability	الإمكانية
Probability	احتمال حدوث شيء ما
Lack of necessity	غياب الضرورة أو الحاجة لشيء ما
Necessity	التعبير عن أن شيء ما ضروري ومؤكد
Certainty / logical deduction	التعبير عن خلاصة منطقية أو أن شيء مؤكد ويقيني
Prohibition	التعبير عن المنع والتحريم.
Suggestion	التعبير عن الإقتراح
Request	التعبير عن طلب شيء ما

Remember: There are 4 important particularities for modal verbs

1. Modal verbs are never conjugated as normal verbs. They never take “-s” or “-es” of the third person singular in simple present. They never take “-ing” of the continuous form and the same with “-ed” of the past.
2. In their negative form, we only add “not” to them.
3. In their interrogative form, we always reverse them with the subject.
4. They are always followed by the bare infinitive of the verb.

Complete List of Modal Verbs

Modal Verb	Meaning	Expressing	Example
must	to have to	100 % obligation	I must stop when the traffic lights turn red.
to be very probable	logical conclusion (deduction)	He must be very tired after such enormous work
must not	not to be allowed to	prohibition	You must not smoke in the hospital.
can	to be able to	ability	I can swim
to be allowed to	permission	Can I use your phone please?
it is possible	possibility	Smoking can cause cancer !
could	to be able to	ability in the past	When I was younger I could stay up all night and not get tired..
to be allowed to	more polite permission	Excuse me, could I just say something?
it is possible	possibility	It could rain tomorrow!
may	to be allowed to	permission	May I use your phone please?
it is possible, probable	possibility, probability	It may rain tomorrow!
might	to be allowed to	more polite permission	Might I use your phone please?
it is possible, probable	weak possibility, probability	I might come and visit you in America next year, if I can save enough money.
need	necessary	necessity	Need I say more?
need not	not necessary	lack of necessity/absence of obligation	I need not buy any tomatoes. There are plenty in the fridge.
should/ought to	used to say or ask what is the correct or best thing to do	50 % obligation	I should / ought to see a doctor. I have a terrible headache.
to suggest an action or to show that it is necessary	advice	You should / ought to revise your lessons
to be very probable	logical conclusion (deduction)	He should / ought to be very tired after such enormous work
had better	to suggest an action or to show that it is necessary	advice	You ‘d better revise your lessons

Courtesy from myenglishpage.com

Modal Verbs and their Communicative Functions in the Past

We can use modal verbs in the past in different ways and for different communicative functions.

Structurally, we use the modals might/may/could/should/must/would + have + the past participle of the verb.

Remember: the modal verbs + have can be contracted  to the following:

Might have == might’ve

May have == may’ve

Could have == could’ve

Should have == should’ve

Must have == must’ve

Would have  == would’ve

Major uses of modals in the past

#1 Use might / may have + past participle to speculate about the past.

Example 1: She might have been busy.

Example 2: She might have eaten some rotten food. That’s why she is vomiting.

#2 use could have + past participle to talk about ability / capability in the past

Example 1: I could have become a professional footballer but I broke my leg.

Example 2: you could have succeeded in your exam if you had worked harder.

#3 use must have + past participle to talk about what you believe is certain (about the past)

Example: She must have missed her train.

Example: where are my keys? I must have left them in the kitchen.

#4 use should have + past participle to talk about past mistakes, recommendations and criticism about the past.

Example: you should have been here an hour ago.

#5 use would have + past participle to talk about past possibilities and their consequences.

Example: I would have become a doctor if I had passed my exams successfully.

Example: I would have been here an hour ago but I missed my train.

Remember: All these modal verbs can take the negative form.