针对给定的一段英文文本进行关键词提取，并以逗号分隔的形式输出关键词列表。


Natural language processing (NLP) is a subfield of computer science, information engineering, and artificial intelligence concerned with the interactions between computers and human (natural) languages, in particular how to program computers to process and analyze large amounts of natural language data.
关键词： Natural language processing, NLP, subfield, computer science, information engineering, artificial intelligence, interactions, computers, human, languages, program, process, analyze, large amounts, data.