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: Specialization occurs when competing species evolve different adaptations. 
Sentence2: evolving different adaptations increases survival.

SOLUTION: adaptations

PROBLEM: Sentence1: Ice ages buried the planet in snow and ice for millions of years at a time. 
Sentence2: Unmelted winter snow and ice accumulate from year to year, and an ice age can begin.

SOLUTION:
ages