A + B → X → C + D
ʌ WORD_BOUNDARY p l ʌ s WORD_BOUNDARY b iː WORD_BOUNDARY ɹ aɪ t WORD_BOUNDARY æ ɹ oʊ WORD_BOUNDARY ɛ k s WORD_BOUNDARY ɹ aɪ t WORD_BOUNDARY æ ɹ oʊ WORD_BOUNDARY s iː WORD_BOUNDARY p l ʌ s WORD_BOUNDARY d iː WORD_BOUNDARY