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: Sperm had to swim from male to female reproductive organs for fertilization. 
Sentence2: If fertilized, the egg implants itself in the uterus.
answer:
fertilization


question:
Sentence1: If there is no movement friction is zero. 
Sentence2: Movement causes the temperature of an object to increase.
answer:
movement


question:
Sentence1: Ducks have webbed feet, designed for swimming. 
Sentence2: Feet designed for swimming are used for moving faster through water.
answer:

designed