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: Fully cooking oysters kills the bacteria. 
Sentence2: Fully cooking oysters can prevent illness.

SOLUTION: Fully

PROBLEM: Sentence1: Limestone caves displaying stalactites. 
Sentence2: Limestone caves are formed by depositions.

SOLUTION: Limestone

PROBLEM: Sentence1: Illness is an imbalance in homeostasis. 
Sentence2: Hormones control many cell activities, so they are very important for avoiding illness.

SOLUTION:
Illness