instruction:
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.
question:
Sentence1: a warm front causes cloudy and rainy weather. 
Sentence2: Stratus clouds are associated with a warm front.
answer:
front


question:
Sentence1: air pollution can cause the pH of soil to decrease. 
Sentence2: Acidity is measured with a pH meter or with pH paper strips.
answer:
pH


question:
Sentence1: tidal energy can be used to produce electricity. 
Sentence2: spikes come from tidal energy.
answer:

energy