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.

[Q]: Sentence1: Amphibians are the first true tetrapods, or vertebrates with four limbs. 
Sentence2: Frogs are classified as amphibians.
[A]: Amphibians


[Q]: Sentence1: All monkeys are mammals. 
Sentence2: monkeys conserve body heat with their hair or fur.
[A]: monkeys


[Q]: Sentence1: Insects can spread disease and destroy crops. 
Sentence2: Crops Crops are a farmer's stock in trade.
[A]:
crops