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: Propane can be either a liquid or a gas. 
Sentence2: heat can be added to propane to change it's properties through the boiling process.
answer:
Propane


question:
Sentence1: a flashlight converts chemical energy into light energy. 
Sentence2: PALight Flashlights are the ultimate personal LED flashlights.
answer:
flashlight


question:
Sentence1: weathering means breaking down rocks from larger whole into smaller pieces by weather. 
Sentence2: rain can break down rocks into smaller pieces.
answer:

breaking