合并应在什么基础上进行?您的问题相当模糊.另外，我假设a，b，...，f应该是字符串，即'a'，'b'，...，'f'.

On what basis should the merging take place? Your question is rather vague. Also, I assume a, b, ..., f are supposed to be strings, that is, 'a', 'b', ..., 'f'.

>>> x = ['a', 'b', 'c', 'd', 'e', 'f', 'g']
>>> x[3:6] = [''.join(x[3:6])]
>>> x
['a', 'b', 'c', 'def', 'g']

在序列类型，尤其是可变序列类型.也许也在字符串方法上.

Check out the documentation on sequence types, specifically on mutable sequence types. And perhaps also on string methods.