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: Diurnal cycles Diurnal cycles are the daily cycles of light and darkness. 
Sentence2: Plants detect and respond to diurnal cycles.
[EX A]: Diurnal

[EX Q]: Sentence1: Blood type is important for medical reasons. 
Sentence2: Type O is important for medical reasons.
[EX A]: important

[EX Q]: Sentence1: Fire is a chemical reaction. 
Sentence2: Fire requires activation energy to get started.
[EX A]:
Fire