虽然一些科学家说他们担忧人工智能会对人类生存带来威胁，人们对发明可以思考的机器的努力从未停止过。

A、 Although some scientists have voiced their fears that artificial intelligence may pose a threat to the existence of the human race, efforts to create thinking machines have never stopped.
B、 Although some scientists said that they were worried about artificial intelligence may pose a threat to the existence of the human race, people invent thinking machines never stopped.