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: Rivers, rainwater, well water and most lakes contain fresh water. 
Sentence2: canyons are formed by rainwater.
rainwater

Sentence1: All oaks are trees. 
Sentence2: Cutting down oaks has a negative impact on an ecosystem.
oaks

Sentence1: seat belts are used for preventing injuries to passengers in cars. 
Sentence2: Whiplash injuries are soft tissue injuries.

injuries