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: Batteries are a better source of DC electricity. 
Sentence2: a flashlight requires batteries to produce light.
[A]: Batteries


[Q]: Sentence1: Heterotrophs get food by eating other living things. 
Sentence2: fish eat other living things.
[A]: living


[Q]: Sentence1: Cancer is a malignant tumor. 
Sentence2: Cells that divide uncontrollably may form cancer.
[A]:
Cancer