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: Proper digestion is vital for nutrient absorption. 
Sentence2: Digestion is important for an animal's survival.
answer:
digestion


question:
Sentence1: harming an animal species causes that animal 's population to decrease. 
Sentence2: Oil spill sare harmful to animals and the enviroment.
answer:
harming


question:
Sentence1: Caverns Secrets are hidden in caves. 
Sentence2: hidden caves are formed by carbonic acid in groundwater seeping through rock and dissolving limestone.
answer:

are