------
## 最终结论
```python
def sort_even(l: list):
    even_indices = [l[i] for i in range(len(l)) if i % 2 == 0]
    even_indices.sort()
    
    result = l.copy()
    for index, value in zip(range(0, len(l), 2), even_indices):
        result[index] = value
    
    return result
```