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Differing Point of ViewShould / Must

 Expressing advisability and necessity

 

 

 

 

Present - Should vs. Must
SHOULD  MUST

We use should to suggest something.  "It is advisable to..."   The modal should expresses opinion, one person's point of view.

We 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.

We should protect our environment. It makes good sense.  

We must protect our environment, or our resources will disappear.

We should select cars that are more fuel-efficient.

The car industry must change engines that burn fossil fuels.

We should use re-usable bags when shopping.

Stores must give out recyclable plastic bags.

 

 

Ought to  and Have to
OUGHT TO / IT'S A GOOD IDEA HAVE TO

Use ought to or It was a good idea to ... for past advice. 

Use had to or needed to or It was necessary that ... for past necessity.  Use had to for actual past events.

I ought to install solar panels on my roof.

We have to use more alternative energy sources.

You ought not to use your fireplace very often.

Everyone had to save energy.   (and they did.)

It's a good idea to leave your car in your garage.

People have to make changes in their habits.

 

 

Had Better
HAD BETTER COMMON ERRORS

The verbal expression 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. 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. IHad better is always followed by the plain form  (base) verb.

FORM

You had better close the door open or (else) all the heat will go out.   (immediate future)
        [had better]    [plain form]

 

You have better close the door open or all the heat will go out.
You had better  to close the door open or all the heat will go out.
You had better closing the door open or all the heat will go out.

NEGATIVE

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

 

 You hadn't better close the door or the cat will be trapped. (not used much)

NEGATIVE QUESTION

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

POSITIVE QUESTION

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

EXPRESSION/MODAL ADJUSTS MEANING TO PAST TENSE

I thought it was a good idea to close the door.
I thought you should have closed the door.
I thought you ought to have closed the door.
 

HAD BETTER RESTRICTS MEANING TO FUTURE / NO ADJUSTMENT

I thought you had better close the door.   (Had better cannot adjust within the time frame of another clause.)

They had better leave before the hurricane arrived.

Solution - lightbulb Pop-Q "Had Better"

 

 

 

Past - Late Advice vs. Past Necessity
SHOULD HAVE * MUST HAVE

Use should have for advice given after the event happened. "It was advisable, but did not happen."  The advice is hypothetical – what we would have done in a particular situation.

Use had to or needed to or It was necessary that ... for past necessity.  Use had to for actual past events. Must have is used for making conclusions not for stating past necessity.

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

We must have protected our environment. (*Must have means conclusion not necessity.)

We should selected cars that were more fuel-efficient a long time ago.  (but we didn't.)

 

We should have banned the use of plastic bags. (but we didn't.)

 

 

 

Other Past Expressions
OUGHT TO HAVE HAD TO

It was advisable, but did not happen. (Advice that comes too late to use.)

It was necessary.

I ought to have installed solar panels on my roof.  (but I didn't.)

We needed to use more alternative energy sources to save money.

You ought not to have put in a lawn in your yard. (grass) (but you didn't.)

Everyone needed to save energy during the hot summer.

It would have been a good idea to use plants that didn't need much water.

It was necessary that we used plants that required little water.

 

 

 

 

Sentence

Word Order

 

SENT. TYPE 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

advisable

 

Should

 

we 

 

 

 

select

 

energy-efficient cars? 

 

 

advisable

Ought

we 

 

to select

energy-efficient cars? 

 

necessary

Do

we 

need

to select 

energy-efficient cars? 

 

necessary

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   

 

 

Not Required vs. Prohibited
DON'T HAVE TO HAVE TO NOT

Use don't have to if something is not required.

Use have to not if something is prohibited.

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

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

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

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

We don't have to drive big cars.

We have to not drive big cars.
 

 

 

 

  

policyPractice

Store Return Policy

 

 

 

 

  1. Select your response from each menu.
  2. Then check your answer.

 

# YOUR RESPONSE CHECK YOUR ANSWER
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