instruction:
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.
question:
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.
answer:
Antibiotics


question:
Sentence1: Mollusks are invertebrates such as the common snail. 
Sentence2: snails have no backbone.
answer:
snail


question:
Sentence1: Migrants typically travel long distances. 
Sentence2: Barn swallows are Neotropical migrants.
answer:

Migrants