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: a camera is used for recording images. 
Sentence2: a camera is used for recording binary.
[EX A]: camera

[EX Q]: Sentence1: Echinoderms use pheromones to communicate with each other. 
Sentence2: Echinoderms are known for their round symmetry.
[EX A]: Echinoderms

[EX Q]: Sentence1: heat can change the state of matter. 
Sentence2: Heat can change a substance to a liquid.
[EX A]:
heat