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: Parasites are organisms that live off a host. 
Sentence2: roundworms may be free-living or live off a host.

SOLUTION: host

PROBLEM: Sentence1: Organisms that live in marine biomes must be adapted to the salt in the water. 
Sentence2: Most of the water on the planet is salt water in the oceans.

SOLUTION: salt

PROBLEM: Sentence1: the moon revolving around the Earth causes the phases of the moon. 
Sentence2: Phases of the moon, however, depend on the relative positions of the Earth, moon, and Sun.

SOLUTION:
Earth