In standar English today grammar seems to be taking a second place since the most important thing is communication, and using either one or the other, people will get you. Many Europeans say they was instead of they were and everyone understands. However for written English grammar rules use say so much about you, so just take that into account and check this: It s so simple... English has pronouns (I guess your language too) and it has in present 3 forms for the verb to be: am for I, is for he, she, it, and are for we, you or they. Do or does. It works as a verb and also as auxiliary for negative or interrogative sentences in present, and concerning grammar you will also take into account the pronouns:Do for I- you- we-they, and Does for he, she, it (third person). Have or has. It works as a verb and also as auxiliary for sentences in present perfect, and concerning grammar you will also take into account the pronouns:Have for I- you- we-they, and has for he, she, it (third person).