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: friction causes the temperature of an object to increase. 
Sentence2: When we increase the temperature of objects, they always expand.
[A]: increase


[Q]: Sentence1: Erosion of rock makes nutrients available. 
Sentence2: rain causes nutrients to be available.
[A]: nutrients


[Q]: Sentence1: Shivering occurs when many muscles contract a little bit all at once. 
Sentence2: Honey bees generate heat by consuming honey and shivering their muscles.
[A]:
muscles