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.

[EX Q]: Sentence1: Telephone Telephone calls are expensive. 
Sentence2: Communicating by transmitting sound is expensive.
[EX A]: expensive

[EX Q]: Sentence1: Viruses are parasites of cells. 
Sentence2: Populations of viruses do not grow through division because they are parasites.
[EX A]: are

[EX Q]: Sentence1: a pulley is used for lifting objects. 
Sentence2: Resistance exercises are weight-lifting exercises.
[EX A]:
lifting