给定一段英文文本，编写一个程序来计算其中每个单词的频率。


给定一段英文文本，例如：
"This is a sample text with several words. We will use it to demonstrate word frequency calculation."
可以使用Python语言编写一个程序来计算文本中每个单词的频率，具体实现过程如下：

```python
text = "This is a sample text with several words. We will use it to demonstrate word frequency calculation."

# 将文本全部转换成小写字母，去除标点符号
text = text.lower().replace(",", "").replace(".", "")

# 将文本拆分成单词列表
words = text.split(" ")

# 统计每个单词出现的次数
word_count = {}
for word in words:
    if word in word_count:
        word_count[word] += 1
    else:
        word_count[word] = 1

# 输出结果
for word in word_count:
    print(word + ": " + str(word_count[word]))
```

运行以上程序，就可以得到文本中每个单词的频率。