2、简单将来时是一种简单时态，也就是没有助动词的时态结构，仅仅是单纯的动词变形而构成的。所以，关键记住它的词尾的变化。 动词不定式（infinitif）+ 简单将来的词尾(les terminaisons au futur simple)简单将来时不规则动词变位 Etre – > ser + 词尾 Avoir -> aur + 词尾 Faire -> fer +词尾...
but still that's not a rule. There are a lot of situations were you can use both of them ...