The scholars referred to that sourcelanguage as Proto-Indo-European. Proto-Indo-European is a reconstructed language.
学者们把这种源语言称为原始印欧语。原始印欧语是一种重建的语言。
2
Maybe the languages developed from the same sourcelanguage long ago, that is, maybe they are genetically related, that was what happened with Sanskrit, Latin and Greek.