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Should / Must

Advisability, necessity, and requirement

Wind turbine
 

 

Present - Should vs. Must
SHOULD

recommendedShould expresses advisability, a suggestion.  "It is advisable to..."  or "This is a suggestion… " It is weaker than must.  Should is followed by a plain form verb. 

SHOULD PLAIN FORM VERB

People should

protect the environment. It makes good sense.  

We should

select cars so that they are more fuel-efficient.

We should

use re-usable bags when shopping.
MUST

obligationWe use must to express a stronger point of view.  "We need to..."  "We have to..." The modal must also expresses opinion, one person's point of view.
MUST PLAIN FORM VERB

We must

protect our environment, or our resources will disappear.

Engineers must

redesign engines so that they are more fuel-efficient.

Stores must

give out recyclable plastic bags.

 

fossil fuel – gasoline and similar fuels formed by natural processes; fuel resources taken from the earth
plain form – base form, simple form

See Modal Review  "Obligation" – for giving polite direct suggestions

 

 

 

 

Ought (to) / Have (to)

Advisability

 

 

 

Ought and Have
OUGHT (TO) / IT'S A GOOD IDEA

mildly recommendedOught (to) acts very much like a modal except that it is used with an infinitival complement. The modal or the infinitive clause can be negated without much difference in meaning. The question form is not used very much. Ought expresses weaker advisability than have (to).

OUGHT INFINITIVAL FORM

You ought

to use your car less.

You ought not

to use your car so often.
(not advisable)

You ought

to not use your car so often.
(advisable not to use it.)

Ought you

to use your car so often?

It's a good idea

to leave your car in your garage.
HAVE

obligationHave (to), a semi-modal, expresses necessity (strong advisability). However, it is unlike  other modals in its use of do as an auxiliary and its use of an infinitival complement. Negating the modal results in a different meaning from negating the infinitive clause.
HAVE INFINITIVAL FORM

You have

to use other forms of transportation occasionally.

You do not have

to drive.
(not required – You decide.)

You have

to not drive everyday.¹ 
(required not to – Don't)

Do you have

to drive everyday?

It is necessary

to drive less.
 

¹The infinitive is "split" with not.
ought / ought to (CaGEL 3 §2.5.4)

 

 

 

Not have to / Have to not
NOT REQUIRED

some freedomDon't have to expresses something that is not required. "medium–high freedom to act"   (You don't have to park on the street, but it would be nice if you did.)

You don't have to park on the street. (But it would be nice if you did. / Other options exist.)  medium to high "freedom to act"

He doesn't have to go to work everyday.  He can work from home on some days. (It's not necessary.)

We don't have to drive big cars. We can choose to buy smaller ones.

PROHIBITED

obligation– no freedomHave to not expresses something that is prohibited. When spoken, not is emphasized. "no freedom to act" (Do not park on the street.)

You have to not park on the street.  It's necessary not to.

He has to not miss a minute of work. He's an airplane flight controller.

We have to not drive big cars.
 

 

See Modal Review – freedom to act

 

 

 

Had Better

Strong Advisability

 

 

 

Had Better
HAD BETTER

Had better refers to the immediate future and is used to give strong advice (in some cases threatening advice!)  It is more urgent than should or ought to. The had in had better does not behave like other auxiliary verbs.
FORM

You had better close the door open or (else) all the heat will go out.  
 
NEGATIVE

You had better not close the door or the cat will be trapped inside.
 

NEGATIVE QUESTION

Hadn't you better close the door?  (I think you'll agree you had better.) 

TENSE RESTRICTED TO FUTURE

You had better close the door. (future)
You had to close the door. (past requirement or necessity)

I thought it was a good idea to close the door. (reworded to past)
HAD BETTER ERRORS

Had does not change form for tense or person. It always refers to the near future. Had is followed by not in a negative question but not in an positive question. Had better is always followed by the plain form  (base) verb.
 HAD + BETTER + PLAIN FORM — ONLY!

*You have better close the door open or…

*He has better close the door open or…

*You had better  to close the door open or…

*You had better closing the door open or…
HAD BETTER → NOT

* You hadn't better close the door or the cat will be trapped.
POSITIVE QUESTION

*Had you better close the door? (not used)

*Had you better not close the door? (not used) 

TENSE NOT ADJUSTABLE WITHIN ANOTHER CLAUSE

*I thought you had better close the door.  
(I thought you needed to / should have / ought to have closed the door.)

*They had better leave before the hurricane arrived.
(They needed to leave before the hurricane arrived.)

 

Had better retricts meaning to future. No tense adjustment (backshifting) can be done when embedded within another clause.

Solution - lightbulb Pop-Q "Had Better"

 

 

 

 

Should, Had Better, Must

Relative Strength of Advice

 

 

 

Advisability – Weak to Strong
WEAK STRONG STRONGER

Should and ought express weak advisability and are used when we don't wish to impose will on someone else impolitely.

Had better expresses strong advisability. Peers use had better to place emphasis on priority.  People in authority use it as an imperative.

Must and have express stronger advisability.  Peers use them to express necessity. People in authority use them to express requirement.

You should walk more often

You had better walk more often.

You must walk more often.

You ought to walk a more often.

You really ought to walk more often.

You have to walk more often.

It's a good idea to walk more often.

I strongly suggest that you walk more often.

It's necessary that you walk more.

Why don't you walk more often?

For your own good, walk more. (imperative)

It's required that you walk more.

Don't you think you should walk more often.  (invites agreement)

Don't you think you must walk more often?
(Must cannot be weakened.)

 

peer – a friend, same age or rank
authority – parent, teacher, doctor, officer
priority – something that you think is important and that needs attention before anything else

 

 

 

Should have / Needed to

Past Advisability

 

 

PAST HYPOTHETICAL ADVICE

Should have or ought to have express options that were not taken in the past.  "It would have been a good idea, but it did not happen."

We should have protected the environment (but we didn't.)

We ought to have protected the environment (but we didn't.)

*We had better protected the environment. (but we didn't.)

It would have been a good idea to protect the environment (but we didn't.)
PAST  NECESSITY / LATE ADVICE

Needed to or had to express the idea that something was necessary or required.  Had to  expresses an actual past event.

We needed to protect the environment. 
(It was needed. Maybe we did. Maybe we didn't.)

We had to protect the environment.
(It was required. Likely, we did.)

*We must have protected the environment. (inference)

It was necessary that we protect the environment.
(It was required. Likely, we did.)
 

*not used
Must have means inference, conclusion, deduction not necessity.

 

 

 

 

Advice Modals

Word Order

 

 

 

AUXILIARY VERB SUBJECT AUXILIARY VERB VERB BASE / INFINITIVE   TAG CLAUSE

STATEMENT

advisable

 

We 

 

should

 

select (verb base)

 

energy-efficient cars. 

 

 

advisable

We 

ought

to select  (infinitive)

energy-efficient cars. 

 

necessary

We 

need

to select 

energy-efficient cars. 

 

necessary

We 

have

to select 

energy-efficient cars. 

 

QUESTION

Should

 

we 

 

 

 

select

 

energy-efficient cars? 

 

 

Ought

we 

 

to select

energy-efficient cars? 

 

Do

we 

need

to select 

energy-efficient cars? 

 

Do

we 

have

to select 

energy-efficient cars?

 

TAG QUESTION

advisable

 

We 

 

should

 

select

 

energy-efficient cars, 

 

shouldn't we?

advisable

We 

ought

to select

energy-efficient cars, 

oughtn't we?

necessary

We 

need

to select 

energy-efficient cars, 

don't we?

necessary

We 

have

to select 

energy-efficient cars, 

don't we?

NEGATIVE

advisable

 

We 

 

shouldn't

 

select

 

energy-efficient cars. 

 

 

advisable

We 

ought not

to select

energy-efficient cars. 

 

necessary

We 

don't need

to select 

energy-efficient cars. 

 

necessary

We 

don't have

to select 

energy-efficient cars. 

 

W / ADVERB

advisable

 

We 

 

should continually

 

select   (verb base)

 

energy-efficient cars. 

 

 

advisable

We 

ought to knowledgeably

select   (verb base)

energy-efficient cars. 

 

necessary

We 

need to carefully

select   (verb base)

energy-efficient cars. 

 

necessary

We 

have to responsibly

select   (verb base)

energy-efficient cars. 


 

A tag question can also occur with a negative main sentence and a postive final question: They shouldn't do that, should they? (I don't think they should.)  Related page: And so / too   

 

 

 

 

Practice 1

Office Collaboration (group work)

group work

 

 

Read for Modal Usage

Nick (boss) : What do you think of this design?

Anne (assistant) : I don't understand what it means.

Ross (assistant):  I don't get it either.  What is the image inside the circle?

Nick: Really? I guess we'd better change it then.

Ross: We ought to use easily recognizable images. 

Anne: What are the little black circles? Flowers?

Nick: No, it's machinery, a danger point in a piece of equipment.

Ross: Then, shouldn't we ought to make the machine image more identifiable?

Anne: What is the little bird-like image on top.

Nick: It's a hand caught in the machinery. We'd better make that easier to recognize too.

Anne: You should remove the diagonal red line because it covers part of the image.

Ross: It's necessary to add text too.

Nick: OK.  We ought to get back to work. We have to have this ready by 4:00 for the meeting with our client.

catch / caught (past tense)

client – customer; person who hires a service to be done

diagonal line – a straight line that joins two opposite corners of a flat shape, such as a square or a circle

recognizable (adj.) – easy to identify what it is

 

 

 

Decide whether the modal usage is correct or incorrect.
  1. Select the option that best describes the sentence.
  2. Click the "check all" button at the bottom of the practice to reveal the answers after you finish, or
    click the individual "check" buttons #1-10 to compare responses as you go.

 

1.
Nick: Really? I guess we'd better change it then.

   

2.
Ross: We ought to use easily recognizable images. 

   

3.
Ross: Then, shouldn't we ought to make the machine image more identifiable?

   

4.
Nick: It's a hand caught in the machinery. We'd better make that easier to recognize too.

   

5.
Anne: You should remove the diagonal red line because it covers part of the image.

   

6.
Ross: It's necessary to add text too.

   

7.
Nick: OK.  We ought to get back to work. 

   

8.
We have to have this ready by 4:00 for the meeting with our client.

   

 

 

Pinch Point sign revised

 

 

 

 

Practice 2

Store Return Policy

policy
 

 

Read

Before you buy something, you (try) it on. You (consider) carefully whether the item of clothing is right for you.  Sometimes,  (it's…) to take something home and try it on with other things, such as a jacket or shoes. If you decide the item is not right for you, you (not-keep) it. However, you (remove) the tags. You (place) the item back into its bag so that it will stay clean and can be resold. When you return to the store, you (have) the sales receipt.

You also (return) the item  within the time allowed. The store (accept) the item back without much complaint. The store (return) your money. However, it might just offer store credit. If you are unhappy with store credit, then you (ask) about the return policy when you bought it. The policy that was written on the back of your receipt informed you what you (do) for a cash refund.

allowed – permitted

complaint (n.) – saying that one is unhappy or annoyed

inform (v.) – state clearly and plainly in detail

refund (v.) – return of money for the return of an item

 

 

Select the degree of advisability.
  1. Select the response from the list that best completes the sentence. 
  2. Compare your response to the answer by clicking the "check" button.

 

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