What is possibility?

Possibility is the expression of actions and states in unspecific terms.  Actions and states are not expressed as true or untrue, but somewhere in between.  Possibility can be expressed in different tenses. 

Possibility is expressed with modal verbs such as can, could, may, and might.

Statement

  1. Dogs are difficult to train.
  2. It gets hot in Arizona.
  3. You buy anything you want.
  4. We passed through the tunnel.

Possibility Statement

  1. Dogs can be difficult to train.
  2. It might get hot in Arizona.
  3. You could buy anything you want.
  4. They might have passed through the tunnel.

What is a modal verb?

A modal verb is an auxiliary (helping) verb that expresses a particular quality of a verb.  It modifies the meaning of the main verb.  Modal verbs are used with the infinitive (base form) of the main verb.

MODALS INCLUDE WORDS LIKE:

can, could, may, might, must, shall, should, will, and would

The placement of modal verbs depends on the type of sentence or the tense.

  1. Statement:  subject + modal + base verb
  2. Negative Statement:  subject + modal + not + base form
  3. Past: subject + modal + have + past participle
  4. Negative Past:  subject + modal + not + have + past participle
  1. Statement: Dogs can be difficult to train.
  2. Negative Statement: It might not get hot in Arizona.
  3. Past: You could have bought anything you want.
  4. Past Negative: They may not have passed through the tunnel.

How are the modals can and could used to express possibility in the present tense?

Can and could are commonly used to express possibility in the present tense.

  • Statement:  subject + modal + base verb
  • Negative Statement:  subject + modal + not + base form

Possibility – can

  • Present tense
  • Uncertain beliefs
  • Can is used for general possibility
  • Also use could / may / might

Statement

  1. Dogs are difficult to train.
  2. It gets hot in Arizona.
  3. You buy anything you want.
  4. I passed through the tunnel.

Possibility with can  – Affirmative

  1. Dogs can be difficult to train.
  2. It can get hot in Arizona.
  3. You can buy anything you want.
  4. I can pass through the tunnel.

Possibility with can – Negative

  1. Dogs can’t be that difficult to train.
  2. It can’t get much hotter than this.
  3.  You can’t buy everything in this store.
  4. We can’t pass through the tunnel.

Possibility – could

  • Present tense
  • Uncertain beliefs
  • Also use can / may / might

Statement

  1. Learning English is fun.
  2. Sid is in his office.
  3. John is on the phone for a while.
  4. Fixing your computer is easy.

Possibility with could – Affirmative

  1. Learning English could be fun.
  2.  Sid could be in his office.
  3. John could be on the phone for a while.
  4. Fixing your computer could be easy.

Possibility with could – Negative

  1. Learning Chinese couldn’t be that difficult.
  2. No, Sid couldn’t be in the office now.  The office is locked.
  3.  John couldn’t still be on the phone, could he?
  4. Fixing my computer couldn’t be that easy.

How is the modal could used to express possibility in the past tense?

The modal could is used to express possibility in the past tenseCan is not used in the past tense. 

  • Past:  subject + modal + have + past participle (PP)
  • Past Negative:  subject +  modal + not + have + past participle (PP)

Possibility – could (not) have 

  • Past tense
  • Uncertain beliefs
  • Also use:   may have + PP / might have + PP

Statement

  1. John beat you in the race.
  2. You broke your leg doing that.
  3. Stan drove you to the party.
  4. Fixing your computer was easy.

Possibility with could – Affirmative Past

  1. John  could have beaten you in the race.
  2.  You could have broken your leg doing that.
  3. Stan could have driven you to the party.
  4. Fixing your computer could have been easy.

Possibility with could – Negative Past

  1. John couldn’t have beaten you in the race.
  2. You couldn’t have broken your leg doing that.
  3.  Stan couldn’t have driven you to the party.
  4. Fixing your computer couldn’t have been that easy.

How are the modals may and might used to express possibility in the present tense?

The modals may and might are both used to express possibility.

  • Statement:  subject + modal + base verb
  • Negative Statement:  subject + modal + not + base form

Possibility – may

  • Present tense
  • Uncertain beliefs
  • Also use could  / might
  • Use can for general possibility.

Statement

  1. It rains in the jungle every day.
  2. Going around Atlanta is the quickest route.
  3. The medicine cures the infection.
  4. The red tomatoes taste better than the green ones.

Possibility with may – Affirmative

  1. It may rain rain in the desert today.
  2. Going around Atlanta may be the quickest route.
  3. The medicine may cure the infection.
  4. The red tomatoes may taste better than the green ones.

Possibility with may – Negative

  1. It may not rain in the jungle today.
  2.  Going through Atlanta may not be the  quickest route.
  3.  The medicine may not cure the infection.
  4. The green tomatoes may not taste as good as the red ones.

Possibility – might

  • Present tense
  • Uncertain beliefs
  • Also use  could / may
  • Use can for general possibility.

Statement

  1. It rains in the jungle every day.
  2. Going around Atlanta is the quickest route.
  3. The medicine cures the infection.
  4. The red tomatoes taste better than the green ones.

Possibility with might – Affirmative

  1. It might rain rain in the desert today.
  2. Going around Atlanta might be the quickest route right now.
  3. The medicine might cure the infection.
  4. The red tomatoes might taste better than the green ones.

Possibility with might – Negative

  1. It might not rain in the jungle today.
  2.  Going through Atlanta might not be the  quickest route.
  3.  The medicine might not cure the infection.
  4. The green tomatoes might not taste as good as the red ones.

How are the modals may and might used to express possibility in the past tense?

To use the modals may and might in the past tense, use the past participle form of the main verb.

  • Past:  subject + modal + have + past participle (PP)
  • Past Negative:   subject + modal + not + have + past participle (PP)

Possibility – may (not) have

  • Past tense
  • Uncertain beliefs
  • Also use:   could have + PP / might have + PP

Statement

  1. John finished already.
  2. My friends ate earlier.
  3. That was your best idea yet.
  4. George sang that song a time or two.

Possibility with may – Affirmative Past

  1. John  may have finished already.
  2.  My friends may have eaten earlier.
  3.  That may have been your best idea yet.
  4. George may have sung that song a time or two.

Possibility with may – Negative Past

  1. John may not have finished yet.
  2. My friends may not have eaten earlier.
  3.  That may not have been your best idea.
  4. George may not have sung that song.

Possibility – might (not) have

  • Past tense
  • Uncertain beliefs
  • Also use:   could have + pp / may have + pp

Statement

  1. John finished already.
  2. My friends ate earlier.
  3. That was your best idea yet.
  4. George sang that song a time or two.

Possibility with might – Affirmative Past

  1. John might have finished already.
  2. My friends might have eaten earlier.
  3.  That might have been your best idea yet.
  4. George might have sung that song a time or two.

Possibility with might –  Negative Past

  1. John might not have finished yet.
  2. My friends might not have eaten earlier.
  3.  That might not have been your best idea.
  4. George might not have sung that one.

Basic ESL Workbooks

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