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: Combustion generates toxic fumes. 
Sentence2: High temperatures can cause toxic fumes.
[A]: fumes


[Q]: Sentence1: the mass of an object causes the gravitational force exerted by that object. 
Sentence2: gravitational force accelerates objects.
[A]: force


[Q]: Sentence1: Babies that are very large or very small at birth are less likely to survive. 
Sentence2: premature births are less likely to survive.
[A]:
birth