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: Smoking accelerates the aging process. 
Sentence2: smoking accelerates the death of cells.
answer:
Smoking


question:
Sentence1: Nitrogen is found in proteins, nucleic acids, and chlorophyll. 
Sentence2: Life without protein is impossible.
answer:
proteins


question:
Sentence1: boiling means change from a liquid into a gas by adding heat energy. 
Sentence2: boiling means change from water into a gas by adding heat energy.
answer:

a