TASK DEFINITION: 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.
PROBLEM: Sentence1: Amphibians have permeable skin that easily absorbs substances from the environment. 
Sentence2: permeable skin easily absorbs air to breathe through.

SOLUTION: absorbs

PROBLEM: Sentence1: Plants exhibit phototropism, or growing toward a light source. 
Sentence2: Bamboos are vigorous, rugged plants.

SOLUTION: Plants

PROBLEM: Sentence1: Caffeine, found in coffee and caffeinated soft drinks, is a diuretic. 
Sentence2: coffee contains psychoactive drugs.

SOLUTION:
coffee