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: dew is formed when water vapor condenses over night. 
Sentence2: Condensing is a gas turning into a liquid.
answer:
condenses


question:
Sentence1: Cell death occurs by activation of cell death genes. 
Sentence2: Aging is associated with the activation of certain genes.
answer:
activation


question:
Sentence1: Vehicle emissions are a major cause of air pollution. 
Sentence2: Traveling is a cause of air pollution.
answer:

air