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.
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Question: Sentence1: a stopwatch is used to measure time. 
Sentence2: Time can be measured with a clock or watch.

Answer: measure


Question: Sentence1: Sex hormones are chemical messengers that control sexual development and reproduction. 
Sentence2: Androgens are male sex hormones.

Answer: Sex


Question: Sentence1: Optical glass diopters allow ultra-close focusing. 
Sentence2: glass instruments allow close observations.

Answer:
allow