The /3/ vowel is spelled with <er>, <ir>, <ear>, <ur>, <our> in journey and <or> in worst. The /eɪ/ vowel is spelled <aCe>, <ai> or <ay>, and is seen in the letter names A and K.
This is a contrast between a long vowel and a diphthong. The starting positions are fairly close but it does not seem to be a problem for learners.
The nature/nurture pair features in much current scientific debate on genetics, while the words surf and safe turn up in various slogans about guarding against internet porn. Other interesting pairs include:
The density figure is 6.94%. The set makes 112 semantic contrasts giving a loading of 52.3%.
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Credit: John Higgins