The exact realization of the varies somewhat amongst dialects. In Brazil, and are in complementary distribution: occurs in word-final unstressed syllables, while occurs in stressed syllables before an intervocalic , , or ; in these phonetic conditions, can be nasalized. Unstressed occurs in all other environments. In European Portuguese, the general situation is similar (with being more prevalent in nearly all unstressed syllables), except that in some regions the two vowels form minimal pairs in some European dialects. In central European Portuguese this contrast occurs in a limited morphological context, namely in verbs conjugation between the first person plural present and past perfect indicative forms of verbs such as "pensamos" ('we think') and "pensámos" ('we thought'; spelled in Brazil). proposes that it is a kind of crasis rather than phonemic distinction of and . It means that in "falamos" 'we speak' there is the expected prenasal -raising: , while in "falámos" 'we spoke' there are phonologically two in crasis: (but in Brazil both merge, "falamos" ). Close-mid vowels and open-mid vowels ( and ) contrast only when they are stressed. In unstressed syllables, they occur in complementary distribution. In Brazilian Portuguese, they are raised to a high or near-high vowel ( and , respectively) after a stressed syllable, or in some accents and in general casual speech, also before it.