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: An accounting period is simply a period of time. 
Sentence2: seconds are used to measure a period.
answer:
period


question:
Sentence1: an animal requires warmth for survival. 
Sentence2: Light and heat and warmth are basic necessities for survival.
answer:
warmth


question:
Sentence1: skin is used for protecting the body from harmful substances. 
Sentence2: Skin is the body's largest organ.
answer:

skin