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: if a neutral atom loses an electron then an atom with a negative charge will be formed. 
Sentence2: Ice crystals that are formed have a negative charge.
answer:
charge


question:
Sentence1: Trees have woody stems covered with bark. 
Sentence2: Evergreens have woody stems covered with bark.
answer:
bark


question:
Sentence1: Amphibians are the first true tetrapods, or vertebrates with four limbs. 
Sentence2: Animals in the frog family are the first true tetrapods.
answer:

first