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: Cnidarians have a hydrostatic skeleton. 
Sentence2: Jellyfish have a hydrostatic skeleton.

A: hydrostatic
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Q: Sentence1: propulsion is used for flying by a spacecraft. 
Sentence2: Jets are used for flying by spacecraft.

A: flying
****
Q: Sentence1: When people look around everyday, they see color. 
Sentence2: When people look around everyday, they require light.

A:
When
****