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: Mating is generally preceded by courtship. 
Sentence2: Mating is generally similar across species.

Answer: Mating


Question: Sentence1: when a hemisphere is tilted away from the sun , that hemisphere receives less direct sunlight. 
Sentence2: Sunlight is delivered in small packets of energy called photons.

Answer: sunlight


Question: Sentence1: Bioterrorism is another potential threat in the environment. 
Sentence2: Immediate reporting is also required for diseases caused by Category A Bioterrorism agents.

Answer:
Bioterrorism