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.
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Question: Sentence1: if an object is made of a material then that object has the properties of that material. 
Sentence2: An object is an item in the real world.

Answer: object


Question: Sentence1: dropping an object into water causes vibrations in the water. 
Sentence2: Dropping an object into lake causes vibrations.

Answer: dropping


Question: Sentence1: Greenhouse gases act as the glass in a greenhouse. 
Sentence2: glass keeps plants warm.

Answer:
glass