instruction:
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.
question:
Sentence1: Acids dissolve in base and turn blue litmus red. 
Sentence2: acid changes color.
answer:
Acids


question:
Sentence1: Oil and gasoline are fossil fuels. 
Sentence2: lawn mowers convert fossil fuels into motion.
answer:
fossil


question:
Sentence1: Light is described both as wavelengths and photons. 
Sentence2: a prism is used for refracting wavelengths and photons.
answer:

photons