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: Acids dissolve in base and turn blue litmus red. 
Sentence2: acid changes color.

Answer: Acids


Question: Sentence1: First, the bottle is calibrated with a graduated cylinder. 
Sentence2: calibration is performed with a cylinder.

Answer: calibrated


Question: Sentence1: Animals acquire nutrients by ingestion. 
Sentence2: An animal requires ingestion to grow and heal.

Answer:
ingestion