The Function of Modal verbs
1) Can/Could: The modal verbs can and could are used to express ability. That someone or something has/ had the capacity to perform an action.
Can is generally used to express present ability
Could is generally used to express past ability
Examples: The girl can run for many hours
The mayor could run the campaign if the opportunity was given
Can and could can also be used to make requests. Could is generally considered to be more polite or mor formal than can
Examples: Can you help me call my sister?
Could you examine her knee, please?
2) Must: Strong neccessity or obligation .
The speaker uses Must during written or verbal communication when they want to express a firm neccessity or obligation. It leaves little or no room for arguement or refusal.
The modal verb must shows deep concern and a firm neccessity for the action to be carried out.
It is therefore to express an order, command or strong obligation.
Examples: You must evacuate this site; floods are Frévent here.
The thief must be convicted.
You must submit your assignment this Friday.
N.B Must can also express a strong logical conclusion
In this case, Must can also be used to express logical necessity or deduction. In this case, must is not used to give an order or express an obligation. Instead, it shows that the speaker has reached a conclusion based on available evidence or clues.
Example: There is darkness everywhere; there must be power shortage.
With the clue darkness everywhere, the speaker deduces that there is probably a power shortage
The deduction may not necessarily be correct as there might be order reasons for the darkness. However, based on the available clue, the speaker considers the power shortage as the most logical explanation .
Therefore in this context, Must = strong logical conclusion and not Must = obligation
Compare:
You must evacuate this site – strong obligation/ order
There is darkness everywhere; there must be a power shortage – a strong logical conclusion
3) May/ Might: The modal auxiliary may/ might are mainly used to express possibility. However, May can also be used to express a polite or formal request for permission
Thus remember this distinction always
May- polite request for permission
Might – possibility
A) May – Polite request for permission
It is used to ask for permission in a polite way.
Example: May I have some coffee, please ?
May I use your bathroom? I am pressed.
Oh! my battery is discharged. May I use your phone?
B) May and Might for possibility
Both may and might are used for possibility .
Examples: It may rain today the clouds are heavy.
She may fall ill due to her mother’s death.
Harrison may pass the certification exam this year.
The girl might be late for the conference.
The plan might be interpreted wrongly.
Might is usually used to express a less tentative possibility than may.
N.B: When may is used to request something politely it’s a permission while when may or might are used in a statement to indicate that something is possible it’s a possibility.
Compare: May she enter the room? Polite request
she may leave now – possibility
She might leave at noon – possibility
4) Should: Advice or Recommendation
The modal auxiliary should is used to give an advice or make a recommendation. It is used when the speaker feels that a particular idea or action is good, beneficial or appropriate and proposes for it to be adopted
Examples. You should study hard, if you want to pass your exams
You shouldn’t drive without your seatbelt on. It’s risky.
N.B Should has nothing to do with giving orders and commands as the person involved is free to reject, accept or adopt the advice
Compare : The meeting must be held now – strong obligation
The meeting should be held early – an advice
Therefore must as earlier said leaves little or no room for refusal while should is only a proposal that can be rejected if he doesn’t feel comfortable with it.
5) Will and Shall: The modal auxiliary will and shall are used to talk about actions or events that are expected to take place in the future.
A) Will: It is used with all subjects to express future actions or events
Examples: The plane will land at the airport on time.
The Minister of Urbanisation and Development will chair the conference today.
B) Shall: Shall is also used to express future actions or events, but it is only used with the subject I and We. However, this is more formal but Less common in everyday usage as against will which is generally used.
Examples: I shall contest for the post of Women’s Leader in the House of Parliament
We shall be travelling by bus tonight.
6) Would for conditional situations
The modal auxiliary would can be used to express conditional actions —an action that would take place if a particular condition were fulfilled.
Example: The children would go picking fruits if the weather were favourable
I would travel to Canada if I had money
Here the condition “ would go picking...” depends on the condition ” if the weather were favourable”. Meaning the action is not certain to happen. Same explanation applies with the second statement.
Compare : You will do the shopping tomorrow – Future
I shall examine her movements closely – More formal future
The children would go if their parents give them the permission. Condition action
N.B When modal auxiliaries are used to make offers, suggestions, requests or questions, they are placed before the subject of the sentence.
Example: Shall I go with you? – Offer
Could you give me some water? – polite request
Should she sleep outside? question seeking advice
Rule = modal auxiliary + subject + main verb…..?