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.

[EX Q]: Sentence1: Energy enters ecosystems in the form of sunlight or chemical compounds. 
Sentence2: Energy enters ecosystems in the form of photons.
[EX A]: Energy

[EX Q]: Sentence1: Insects spread disease and destroy crops. 
Sentence2: Crops are plants that are grown for food or other uses.
[EX A]: crops

[EX Q]: Sentence1: damming a river can cause a lake to form. 
Sentence2: Beavers cause ponds and lakes to form.
[EX A]:
form