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: Lymphocytes are the key cells involved in the immune response. 
Sentence2: The key cells involved in the immune response produce antibodies.
answer:
cells


question:
Sentence1: bacteria can cause people to become ill. 
Sentence2: bacteria can cause people to die.
answer:
bacteria


question:
Sentence1: Refrigerators are major users of electricity. 
Sentence2: Keeping food fresh for a long period of time is a major user of electricity.
answer:

electricity