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: Bird eggs have hard, calcium carbonate shells. 
Sentence2: The reproductive cells of a bird is a hard, calcium carbonate shell.
answer:
calcium


question:
Sentence1: if a neutral atom loses an electron then an atom with a negative charge will be formed. 
Sentence2: Ice crystals that are formed have a negative charge.
answer:
charge


question:
Sentence1: Students live at home or in group homes. 
Sentence2: Hermits crabs use dead snails shells as their place to live.
answer:

live