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: Antibiotics and vaccines are being stockpiled as Britain gears up to meet the bioterrorism threat. 
Sentence2: Antibiotics and vaccines are being stockpiled against another potential threat in the environment.

SOLUTION: Antibiotics

PROBLEM: Sentence1: evaporation can be used for separating a solute from a solvent in a solution. 
Sentence2: Evaporation can be used for segregation a solute from a solvent in a solution.

SOLUTION: a

PROBLEM: Sentence1: Small prey, like a mouse or vole, is carried back to a feeding perch where it is swallowed whole. 
Sentence2: Some birds catch mice using their beak.

SOLUTION:
mouse