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: Plants use unsaturated fatty acids to store energy. 
Sentence2: Plants and fish contain fatty acids.

SOLUTION: Plants

PROBLEM: Sentence1: the ovaries are used in reproduction. 
Sentence2: Egg released by the ovary.

SOLUTION: ovaries

PROBLEM: Sentence1: Thyroid hormones increase the rate of metabolism in cells throughout the body. 
Sentence2: TSH, which is secreted by the pituitary gland, stimulates the thyroid gland to produce hormones.

SOLUTION:
Thyroid