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: Very often their only metal object in the house is a cooking pot or a knife. 
Sentence2: sharpening a knife causes it to change shape.
answer:
knife


question:
Sentence1: skin is used for protecting the body from harmful substances. 
Sentence2: Acids are harmful to tissue.
answer:
harmful


question:
Sentence1: zinc has a positive impact on the healing of wounds. 
Sentence2: Zinc and heat are good for wounds.
answer:

zinc