Generate an overlapping word between the given two sentences. When you find the overlapping words, they don't have to match exactly, e.g., "survival" and "survive" are valid overlapping words. Little words like "the" or "of" don't count! You must generate significant words which are not the stop words.

[Q]: Sentence1: an animal requires air for survival. 
Sentence2: The Moon has no atmosphere and no air.
[A]: air


[Q]: Sentence1: Ground tissue makes up most of the interior of a plant. 
Sentence2: ground tissue makes up most of the interior of a dandelion.
[A]: Ground


[Q]: Sentence1: Mammals are animals that are born with fur or hair. 
Sentence2: Mammals are born with fur that grows thicker for warmth in winter.
[A]:
Mammals