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.

[EX Q]: Sentence1: keeping food cold is used for keeping food fresh. 
Sentence2: Keeping food cold is used to keep food simple and natural as possible.
[EX A]: cold

[EX Q]: Sentence1: Sperm pass out of the body through the urethra. 
Sentence2: Sperm travel from the testicles through the vas deferens to the seminal vesicles and the prostate.
[EX A]: Sperm

[EX Q]: Sentence1: Trees are cut down in the forest and are then sent to a paper mill. 
Sentence2: products from a paper mill can have a negative impact on an ecosystem.
[EX A]:
mill