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.

Q: Sentence1: an automobile engine transforms chemical energy into mechanical energy. 
Sentence2: cars transform chemical energy into mechanical energy.

A: chemical
****
Q: Sentence1: Marine dolphins are endangered by fishing nets, speedboats, and pollution. 
Sentence2: dolphins live mainly in shallow coastal waters.

A: dolphins
****
Q: Sentence1: Most pituitary hormones control other endocrine glands. 
Sentence2: prolactin controls other endocrine glands.

A:
control
****