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? Solve this instance: Sentence1: Unlike the unisexual gametophytes of a moss, a fern gametophyte is bisexual. 
Sentence2: female ferns can produce eggs inside the ovaries of flowers.
Student:
fern