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: Telephone Telephone calls are expensive. 
Sentence2: Communicating by transmitting sound is expensive.
answer:
expensive


question:
Sentence1: Antigens are proteins foreign to the body. 
Sentence2: antigens are proteins.
answer:
proteins


question:
Sentence1: Testosterone stimulates the reproductive organs to develop into male organs. 
Sentence2: Male mammals have a tube-like organ called the 'penis'.
answer:

male