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.
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Question: Sentence1: a pulley is used for lifting objects. 
Sentence2: Resistance exercises are weight-lifting exercises.

Answer: lifting


Question: Sentence1: Animals can communicate with sounds, chemicals, or visual cues. 
Sentence2: cats can communicate with sounds, chemicals or visual cues.

Answer: chemicals


Question: Sentence1: Energy is a basic necessity of an ecosystem. 
Sentence2: The basic necessity of an ecosystem enters in the form of sunlight.

Answer:
basic