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: Speciation events are thus examples of macroevolution. 
Sentence2: Speciation events occur over geologic time above the level of the species.
[A]: Speciation


[Q]: Sentence1: Some birds are pollinators that co-evolved with plants. 
Sentence2: insects pollinate plants.
[A]: plants


[Q]: Sentence1: bacteria cause food to spoil. 
Sentence2: Water can be tested for coliform and fecal coliform bacteria.
[A]:
bacteria