Python 2.7 如何在python中从多个类别中搜索和替换字符串中的关键字？

假设我有一个字符串，其内容如下：

'''
Looking closely we find Pepsi and Coca-cola have been the two two biggest brands of soda in the world for the past four years.
'''

我想将单词到其类的映射表示为：

classes={"NAME":["pepsi","coca-cola", "james","jill"...],"CATEGORY":["soda","food","automobile"....],"NUMBER":["one","two","three","four"....]}

因此，在结尾处，我希望原始字符串为：

Looking closely we find NAME and NAME have been the two biggest brands of CATEGORY in the world for the past NUMBER years

对于一个简单的dict，例如：

rep = {"NAME": "pepsi", "CATEGORY": "soda"....}

我可以替换上面的dict的单词，但是如果每个键有一个以上的单词，我该怎么做呢

这就是我到目前为止所做的：

stringh=sentence.lower()

for i,j in rep.items():
    stringh = stringh.replace(j, i)

print stringh

---

遍历列表

stringh=sentence.lower()

for i,j in rep.items():
    for k in j:
        stringh = stringh.replace(k, i)

print stringh