Word formation: prefixes
Negative prefixes (un-, in-, im-, ir-, il-, dis-, mis-), re-, over-, under-, and words that need two changes.
Negative prefixes are one of the biggest traps in Part 3: the word must fit the grammar AND the meaning. Let's learn how to spot when a word needs to become negative.
Negative prefixes
They give the opposite meaning. There is no rule for which one to use – learn the words.
Other useful prefixes
Prefix + suffix together
Part 3 often needs two changes at once.
How it comes up in Part 3
In Part 3 you change the word in capitals so that it fits the gap: the right kind of word, the right form and the right spelling.
ABLE
The meaning is negative ('Sorry'), so add un-.
POSSIBLE
Negative meaning: im- before p.
RESPONSIBLE
Negative meaning: ir- before r.
Common mistakes
- ✗ It was unpossible to see.✓ It was impossible to see.im- before p.
- ✗ I unagree with you.✓ I disagree with you.Some words take dis-, not un-.
- ✗ The instructions were unclearly.✓ The instructions were unclear.After 'were' you need an adjective – check the ending as well as the prefix.
Read the whole sentence: words like 'but', 'sorry', 'unfortunately' or 'not' often show that the answer needs a negative prefix. It's one of the most common traps in Part 3!
Quick check
Use the word in capitals to form a word that fits the gap.
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