isenziwas, were, being, been
1I am at home today — Ndisekhaya namhlanjeI was at school yesterday — Bendisesikolweni izoloI will be in Cape Town tomorrow — Ndiza kuba ndiseKapa ngomsoWho are you? — Ungubani?I am Ben — NdinguBen
2-baHe is studying to be a teacher — Ufundela ukuba ngutitshalaSizwe will be home soon — USizwe uza kuba sekhaya kamsinya
3(referring to age)SC+-naHe is fifteen; he will be sixteen in May — Uneminyaka elishumi elinesihlanu; uza kuba neminyaka elishumi elinesithandathu ngoMeyi
The verb 'to be' in English is very irregular. For Sense 1, you will most often use a subject concord (for verbs) or copulative concord (for nouns). You might also use an adjective or relative concord.