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: Examples of gametes are ova and spermatozoa. 
Sentence2: fertilization of ova and spermatozoa produces a diploid zygote.
[EX A]: ova

[EX Q]: Sentence1: boiling is when liquids are heated above their boiling point. 
Sentence2: If the pressure is reduced, the boiling point is lowered.
[EX A]: boiling

[EX Q]: Sentence1: Dinosaur bones and petrified wood are examples of fossil fuels. 
Sentence2: operating an automobile usually requires dinosaurs.
[EX A]:
Dinosaur