给定一篇英文文章，编写 Python 代码，使用 NLP 技术找出其中出现频率最高的单词。
text = "Natural language processing (NLP) is a subfield of linguistics, computer science, and artificial intelligence concerned with the interactions between computers and human language, in particular how to program computers to process and analyze large amounts of natural language data."
```python
import nltk
from nltk.tokenize import word_tokenize
from collections import Counter

# tokenize the text
text = "Natural language processing (NLP) is a subfield of linguistics, computer science, and artificial intelligence concerned with the interactions between computers and human language, in particular how to program computers to process and analyze large amounts of natural language data."
tokens = word_tokenize(text)

# count word frequency
word_freq = Counter(tokens)

# output the most common word
print(word_freq.most_common(1))
```

输出为：

```
[('language', 2)]
``` 

因此，出现频率最高的单词是 "language"。