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: an earthquake causes the ground to shake. 
Sentence2: A number of buildings in Istanbul also were damaged in the earthquake.

A: earthquake
****
Q: Sentence1: healing requires rest. 
Sentence2: healing requires time.

A: healing
****
Q: Sentence1: All plants have a characteristic life cycle that includes alternation of generations. 
Sentence2: All plants have a characteristic life cycle that includes sexual and asexual reproduction.

A:
characteristic
****