Question

1) Уже в XIV в. все белорусские земли оказались в составе ВКЛ. (да) (нет) 2) Язычники балты из представителей животногомира наиболее почитали змей. (да) (нет)​

Answer 1

1) да
2) да (змей/ужей/ящериц)

Answer 2

Belarusian Lands in the Grand Duchy of Lithuania

Yes, by the XIV century, all Belarusian lands were part of the Grand Duchy of Lithuania (Великое княжество Литовское, ВКЛ). This consolidation of Belarusian lands within the Grand Duchy of Lithuania occurred during this time period [[1]].

Worship of Snakes by Baltic Pagans

No, the worship of snakes by Baltic pagans is not well-documented. While Baltic pagans did have a complex system of beliefs and rituals, there is no strong evidence to suggest that they particularly revered snakes above other animals [[2]].