Mastering English Suffixes and Modal Verbs

Posted on Aug 25, 2025 in English and Spanish Studies

English Suffixes: Building Vocabulary

Suffixes are word endings that change the meaning or grammatical function of a word. Understanding common suffixes can significantly expand your English vocabulary.

Suffixes Forming Nouns (People/Professions)

  • -er: teacher, writer, swimmer, manager, traveller, sailor
  • -ist: journalist, economist, pianist, scientist
  • -ian: electrician, politician
  • -or: survivor, editor

Suffixes Forming Nouns (Qualities/States)

  • -ance/-ence: importance, efficiency
  • -dom: freedom
  • -ness: happiness, sadness
  • -ty: poverty, safety, curiosity
  • -th: truth
  • -ion: perfection, excitation

Suffixes Forming Adjectives

  • -ing: boring, enjoying
  • -able/-ible: dependable, attractive, readable, agreeable, suitable, comfortable, valuable, fashionable, profitable
  • -ive: decisive, destructive, educative, creative, protective, infectious, sympathetic
  • -ory: explanatory
  • -al: critical, practical, musical, political, literal, medicinal
  • -y: rainy, friendly
  • -ful: peaceful, successful
  • -ous: dangerous, courageous, famous, religious
  • -ic: artistic, scientific, energetic, dramatic, alcoholic
  • -ly: weekly

Note: Some words in the original list, such as ‘anger’ and ‘distance’, are base words or have complex derivations rather than being simple examples of these common suffixes. They are included here for completeness from the original text.

Modal Verbs: Expressing Obligation, Possibility, and Ability

Exercise 15: Using ‘Have to’ and ‘Must’

Complete the sentences with the correct form of ‘have to’ or ‘must’:

  1. We’re moving house, so I’ll have to start a new school.
  2. That cough sounds terrible! You have to go to the doctor’s.
  3. Sara was late yesterday because she had to go to the dentist’s.
  4. It is Saturday tomorrow, so we don’t have to get up early.
  5. If you go to Granada, you must visit the Alhambra.
  6. Most children in Britain must wear school uniform.
  7. We must go to the supermarket; there isn’t anything in the fridge.

Exercise 16: Using ‘Mustn’t’ and ‘Needn’t’

Complete the sentences with the correct form of ‘mustn’t’ or ‘needn’t’:

  1. Look! There’s a danger sign. You mustn’t stand there.
  2. You needn’t tell him about the party; he already knows.
  3. They mustn’t go down that street. It says “No Entry.”
  4. There’s plenty of time before the film starts. We needn’t hurry.
  5. In Britain, you don’t have to study two languages at school.
  6. You mustn’t tell your mum about the present; it’s a surprise.
  7. Help me if you like, but you don’t have to.

Understanding Key Modal Verbs

Can: Ability, Possibility, and Permission

The modal verb Can indicates ability or possibility, and is also used to request permission.

  • I can speak five languages. (Ability)
  • Can you help me? (Request/Ability)

Could: Past Ability and Future Possibility

Could indicates possibility or ability in the past, or a hypothetical possibility in the future.

  • Joe could speak Spanish when he was young. (Past Ability)
  • You could pass the test if you studied. (Future/Hypothetical Possibility)

Must: Obligation, Necessity, and Prohibition

The modal verb Must expresses strong obligation or necessity.

  1. Expressing Necessity: When something is essential.
    • Example: You must have a passport to travel abroad.
  2. Expressing Strong Opinion or Belief: What someone believes is necessary.
    • Example: You must tidy your room.
  3. Prohibition (Mustn’t): For something that is forbidden.
    • Example: You mustn’t be late.
  4. Giving Strong Recommendations or Orders: To ensure compliance with a commitment.
    • Example: You must stop smoking.

Have to: External Obligation and Necessity

Have to is used to express certainty, necessity, and obligation, often when the obligation comes from an external rule or situation.

  • I have to do my homework.
  • Do you have to work every day?
  • He doesn’t have to work in a bank.
  • Does he have to work in a bank?
  • A secretary has to be organized.

May and Might: Formal Requests and Possibility

Both May and Might are used to request something formally and politely, with Might often conveying a higher degree of courtesy.

  • May I use your telephone, please? (Formal Request)

Might is also used to indicate possibilities in the present or future, often as a synonym for May in this context.

  • I would bring an umbrella; it might rain later. (Present/Future Possibility)