speakers to substitute in . However, is an allophone of before in a number of Brazilian dialects. Similarly, is an allophone of in the same contexts. In northern and central Portugal, the voiced stops (, , and ) are usually lenited to fricatives , , and , respectively, except at the beginning of words or after nasal vowels. At the end of a phrase, due to final-obstruent devoicing, they may even be devoiced to , , and (for example, verde at the end of a sentence may be pronounced ). Many speakers shift and to and respectively; in Brazil, many speakers further shift to . (A very similar evolution happened in Polish.) Grammar A notable aspect of the grammar of Portuguese is the verb. Morphologically, more verbal inflections from classical Latin have been preserved by Portuguese than by any other major Romance language. Portuguese and Spanish share very similar grammar. Portuguese also has some grammatical innovations not found in other Romance languages (except Galician and Fala): The present perfect has an iterative sense unique to the Galician-Portuguese language group. It denotes an action or a series of actions that began in the past but expected to occur again in the future. For instance, the sentence Tenho tentado falar consigo would be translated to "I have been trying to talk to you", not "I have tried to talk to you." On the other hand, the correct translation of "Have you heard the latest news?" is not *Tens ouvido as últimas? but Ouviste as últimas? since no repetition is implied. Portuguese makes use of the future subjunctive mood, which developed from medieval West Iberian Romance. In modern Spanish and Galician, it has almost entirely fallen into disuse. The future subjunctive appears in dependent clauses that denote a condition that must be fulfilled in the future so that the independent clause will occur. English normally employs the present tense under the same circumstances: Se eu for eleito presidente, mudarei a lei. If I am elected president, I will change the law. Quando fores mais velho, vais entender. When you grow older, you will understand. The personal infinitive can inflect according to its subject in person and number. It often shows who is expected to perform a certain action. É melhor voltares "It is better [for you] to go back," É melhor voltarmos "It is better [for us] to go back." Perhaps for that