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.

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

A: calibrated
****
Q: Sentence1: an animal requires air for survival. 
Sentence2: It is breathed in by animals and restored to the air by the photosynthesis mechanism of plants.

A: air
****
Q: Sentence1: Ejaculation occurs when muscle contractions propel sperm from the epididymes. 
Sentence2: Male orgasm and ejaculation are inhibited.

A:
Ejaculation
****