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: cell division often causes growth. 
Sentence2: Mitosis is cell division.
answer:
cell


question:
Sentence1: Cows are social animals. 
Sentence2: when a cow moves, chemical energy is converted to mechanical energy.
answer:
Cows


question:
Sentence1: Fire needs oxygen in the air to keep burning. 
Sentence2: Fanning a fire keeps it burning.
answer:

burning