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: a plant requires sunlight to grow. 
Sentence2: Grass needs air and sunlight.
[EX A]: sunlight

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

[EX Q]: Sentence1: Trees have woody stems covered with bark. 
Sentence2: All elms are trees.
[EX A]:
Trees