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.

[EX Q]: Sentence1: Acids dissolve in base and turn blue litmus red. 
Sentence2: acid changes color.
[EX A]: Acids

[EX Q]: Sentence1: Some mollusks are nearly microscopic. 
Sentence2: Some squids are nearly microscopic.
[EX A]: Some

[EX Q]: Sentence1: Most invertebrates have a nervous system. 
Sentence2: Most animals without backbones have a nervous system.
[EX A]:
system