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: boiling is when liquids are heated above their boiling point. 
Sentence2: If the pressure is reduced, the boiling point is lowered.
boiling

Sentence1: high pressure systems cause clear weather. 
Sentence2: Weather Clear weather usually means good visibility.
clear

Sentence1: Phenotypic expression of polygenic traits varies over a wide range. 
Sentence2: Skin color occurs over a wide range.

over