You expect the letter O to sound like /oʊ/ (as in go) or /ɒ/ (as in hot). So do and who surprise learners, because a single O with no U or W after it suddenly sounds like /uː/, the OO of too.
There is no way to spot these from spelling alone, but the good news is that the group is small and full of extremely common words. Learn the list once and you fix many everyday mistakes at the same time.
The Rule
In a fixed set of high-frequency words, a lone O is pronounced /uː/ (oo): do, who, whom, whose, to, two, into, move, prove, improve, lose, whose, tomb, womb, whoever. Say them with the long OO of food, not the O of go.
See the Pattern in Action
| Word | O sounds like | Rhymes with |
|---|---|---|
| do /duː/ | /uː/ (oo) | too, blue |
| who /huː/ | /uː/ (oo) | too, blue |
| move /muːv/ | /uː/ (oo) | groove |
| prove /pruːv/ | /uː/ (oo) | groove |
Words to Practice
Common Exceptions
Watch the close relatives that do NOT take /uː/. Love, glove, and dove use /ʌ/ (the cup vowel), while stove, rose, and go use /oʊ/. So move/prove (oo) sit right next to love/dove (uh) and stove (oh). These must be memorized as three separate lists.
Quick Tips to Remember
Make one card that says "O = OO" and write do, who, move, prove, lose on it. Contrast each with a look-alike (move vs. love, prove vs. dove). Say the pairs back to back, then practice your pronunciation.