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: Contact with infected blood, contaminated needles.
Sentence2: scraping oneself on an infected needle may cause infection.

A: infected
****
Q: Sentence1: Fish are the first known true chordates.
Sentence2: Fish are the first known animal with a backbone.

A: Fish
****
Q: Sentence1: exercise has a positive impact on a human 's health.
Sentence2: All movement is exercise.

A:
exercise
****