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 thermometer is used to measure temperature. 
Sentence2: a thermometer is used to measure heat.
[EX A]: a

[EX Q]: Sentence1: Babies that are very large or very small at birth are less likely to survive. 
Sentence2: Poor nutrition while in the womb is the major reason why babies are small at birth.
[EX A]: birth

[EX Q]: Sentence1: Temporary but significant reductions in population size are referred to as population bottlenecks. 
Sentence2: Bottlenecks influence the chance of a species surviving.
[EX A]:
bottlenecks