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: Average vehicle speed rises by only 0.3 miles per hour. 
Sentence2: a speedometer measures miles per hour.

A: hour
****
Q: Sentence1: Fertilization occurs naturally in the fallopian tubes. 
Sentence2: fertilization is used for reproduction.

A: Fertilization
****
Q: Sentence1: mineral graphite is used for making pencil lead. 
Sentence2: Pencil graphite is black.

A:
graphite
****