给定一篇文章和一个单词，将文章中所有该单词出现的位置和上下文句子找出来。
article = "Natural Language Processing is a field of computer science, artificial intelligence, and computational linguistics concerned with the interactions between computers and human (natural) languages."
keyword = "language"
"language" appears twice in the article. 

1. "Natural Language Processing is a field of computer science, artificial intelligence, and computational linguistics concerned with the interactions between computers and human (natural) languages."
2. "...and computational linguistics concerned with the interactions between computers and human (natural) languages."

The context sentences for each occurrence of "language" are:

1. "Natural Language Processing is a field of computer science, artificial intelligence, and computational linguistics concerned with the interactions between computers and human (natural) languages."
2. "...and computational linguistics concerned with the interactions between computers and human (natural) languages."