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.

Sentence1: Carpools and vanpools can save time. 
Sentence2: vanpools decrease the amount of cars used to travel to a place.
vanpools

Sentence1: Leeches are external parasites. 
Sentence2: Leeches live on the surface of their hosts.
Leeches

Sentence1: Gene cloning is the process of isolating and making copies of a gene. 
Sentence2: First, a PCR-based strategy was used to isolate cotton R genes.

isolating