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.

Sentence1: triceps contracting causes a person 's elbow to straighten. 
Sentence2: muscles contracting cause a person's elbow to straighten.
contracting

Sentence1: folding an object causes that object to change shape. 
Sentence2: Folding an object causes that object to transform.
causes

Sentence1: a seismometer is used to measure the strength or magnitude of an earthquake. 
Sentence2: The Richter scale provides information on the magnitude or inherent strength of the earthquake.

earthquake