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❖ Unit 9 ❖ Science and Technology ❖ Functions ❖

Expressing Certainty & Uncertainty

How to express what you know for sure and what you only think might be true. Essential for both speaking and writing.

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Expressing certainty

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Expressing uncertainty

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Practice 1 — Rephrase

Express the same idea differently
  1. I'm quite sure that many of us can't live without a mobile. → There is no doubt that many of us can't live without a mobile. / It is crystal clear that many of us can't live without a mobile.
  2. I don't think that robots will be able to replace human beings at work. → It's unlikely that robots will be able to replace human beings at work. / I doubt that robots will ever replace human beings at work.
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Practice 2 — In context

What would you say?
  1. Friend asks if you can come to his party tomorrow. → You (certainty): "Yes, of course! There's no doubt I'll be there. I wouldn't miss it for anything!"
  2. Friend: "Do you think humans will be able to live on the moon?" → You (uncertainty): "I'm not really sure. It's possible, but it would take many years of research. We'll have to wait and see."

❖ Key Takeaways ❖

① Choose the right strength

Strong certainty: "There is no doubt that…"   ·   Weak: "I think…"

② Modals matter

Will = certainty about the future. May/might/could = uncertainty.

③ Adverbs for nuance

Definitely, certainly, undoubtedly (high). Probably, possibly, perhaps, maybe (low).

❖ Exam tip

This function is often tested in matching exercises. You'll see a list of statements and have to identify whether each shows certainty or uncertainty.

❖ Unit 9 — Science and Technology — Functions ❖