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: Some substances are harmful to the body and block biological systems.

SOLUTION: substances

PROBLEM: Sentence1: melting is when solids are heated above their melting point. 
Sentence2: Ice is a solid, it's cold and it's hard.

SOLUTION: solids

PROBLEM: Sentence1: Adult sponges produce eggs and sperm. 
Sentence2: Adults are sexually mature.

SOLUTION:
Adult