Modal verbs

1. Definition

Modal verbs are verbs that are used in combination with other verbs to express ability, possibility, permission, intention and obligation. These verbs are can, could, may, might, must, ought, shall, should, will and would. Need can also act like a modal verb in certain situations.

2. Meanings

Ability

• She can speak Greek.

• He can’t handle the contract, I’m afraid.

Possibility

• Speaking theoretically:
  Workers may/can experience fatigue. I might be ready to leave at four. We could all be fired someday.
  

• Speaking conditionally:
  If we didn’t have all this work, we could all go on holiday.
  

Certainty

• Making logical deductions:
  They must be finished by now. I must have left the folder in her office.
  

• Fairly certain:
  She should be here soon. The report may not be ready on time.
  

Obligation

• Strong obligation:
  Staff must report all suspicious activities.* I must be going. You will get it done.
  

• Prohibition:
  Unauthorized personnel may not enter. He must not forget.* You can’t go yet.
  

• Suggestions:
  You should call me. I ought to thank him. You might ask Peter.
  

• Freedom from obligation:
  You needn’t hurry.
  

Intention

• Making offers:
  Shall I help you? I’ll tell her.
  

• Expressing willingness:
  If you will turn to page 12... Would you let me know?
  

• Asking for permission:
  Can I borrow your stapler? May I come in? Might I make a suggestion

* This must is stronger than German müssen. English speakers usually say have to or should. Sie müssen nicht is translated as you don’t have to. It would be a mistake to say you must not, which means Sie dürfen nicht.