Question:
Hybrid cars are much more fuel efficient than gasoline powered cars, but they have not caught on in popularity yet.

Who is they referring to in this sentence?
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Answer:
Hybrid cars

Question:
Rocky won the match with Richard because he had no energy.

Who is he referring to in this sentence?
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Answer:
Richard

Question:
Batman is always teaching Robin new techniques and tips, since he is his mentor.

Who is he referring to in this sentence?
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Answer:
Batman

Question:
Joe slapped Jose in the face because he was angry.

Who is he referring to in this sentence?
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Answer:
Joe