------
## 最终结论
```python
def replace_max_specialchar(s, n):
    count = 0
    result = []
    for char in s:
        if char in [' ', ',', '.'] and count < n:
            result.append(':')
            count += 1
        else:
            result.append(char)
    return ''.join(result)

# Test cases
assert replace_max_specialchar('Python language, Programming language.',2)==('Python:language: Programming language.')
assert replace_max_specialchar('a b c,d e f',3)==('a:b:c:d e f')
assert replace_max_specialchar('ram reshma,ram rahim',1)==('ram:reshma,ram rahim')
```