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: Viruses are usually considered to be nonliving. 
Sentence2: Viruses are usually acquired from contact with infected animals.

Answer: Viruses


Question: Sentence1: if fossils of a water animal or plant are found in a place then that place used to be covered by water in the past. 
Sentence2: if remains of prehistoric life are found in a place then that place used to be covered by water.

Answer: be


Question: Sentence1: Mutations that lead to cancer usually occur in genes that control the cell cycle. 
Sentence2: Leukemias are cancers of the blood.

Answer:
cancer