/iː/ This is a long vowel. The lips pull outwards a bit. The mouth is quite closed. The tongue is behind the lower teeth.

/ɜː/ This is a long vowel. The mouth is very relaxed. The lips should not be rounded.

/ɑː/ This is a long vowel. The lips are relaxed. The mouth is open. The tongue is drawn downwards and backwards.

/uː/ This is a long vowel. The sound is more relaxed in English than in most other languages. The lips are slightly rounded and the tongue is pulled backwards.