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.

Sentence1: Fertilization occurs naturally in the fallopian tubes. 
Sentence2: fertilization is used for reproduction.
Fertilization

Sentence1: Warm temperatures have helped plant growth and sizing. 
Sentence2: a greenhouse helps  plant growth.
growth

Sentence1: Soft-tipped darts are a good example of projectiles. 
Sentence2: projectiles are used by sea anemones for defense.

projectiles