I will try explain. So first "estive" it's pretérito perfeito and "estava" pretérito imperfeito. Now how to use them: In PP the action happened just one time in the pass: "trabalhou" In PI the situation was habitual in the pass or stay unfinished. Boths are used in Portuguese, so I will send you some links may can help you: http://pt.slideshare.net/CristinaAlves9/pretrito-imperfeito-e-pretrito-perfeito (this one it's really good) https://ciberduvidas.iscte-iul.pt/consultorio/perguntas/preterito-perfeito-vs-imperfeito/4842 http://www.infoescola.com/portugues/modo-indicativo/

Hi! Estive also means I was, just like estava.. I think you'll prefer to learn it by a video haha I recomend this one https://www.youtube.com/watch?v=pAr6_iDTZx8 and it has english subtitles, you just have to active it. To be honest, in informal portuguese, we use "estava" almost all the time.. Actually, we say even more "tava" than "estava".. but it's wrong in formal portuguese. In a short answer: "Eu estive" is "pretérito perfeito" (past perfect). It means that what happened in the past doesn't happen anymore. "Eu estava" is "pretérito imperfeito"(something like past imperfect). In this one, you can't say for sure if the action is over. But, just practicing to understand it .. If you need a language partner, just send me a message and I'll help you :)