TASK DEFINITION: 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.
PROBLEM: Sentence1: rocks interacting with wind over long periods of time causes weathering. 
Sentence2: When a rock undergoes erosion and weathering, it breaks down to form sediments.

SOLUTION: weathering

PROBLEM: Sentence1: Speciation events are thus examples of macroevolution. 
Sentence2: Speciation events occur over geologic time above the level of the species.

SOLUTION: Speciation

PROBLEM: Sentence1: a spider web is used to capture food by spiders. 
Sentence2: Larger numbers of spiders and spider webs means there are many insects available for food.

SOLUTION:
food