Teacher: 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.
Teacher: Now, understand the problem? If you are still confused, see the following example:
Sentence1: pesticides cause pollution. 
Sentence2: pollution can harm animals.
Solution: pollution.
Reason: The word "pollution" is common to Sentence1 and Sentence2. So, it's a good answer.

Now, solve this instance: Sentence1: Menopause occurs when menstruation stops occurring, usually in middle adulthood. 
Sentence2: vaginal dryness can occur when menstruation stops.
Student:
menstruation