------
## 最终结论
```python
def flatten_list(nested_list):
    result = []
    for element in nested_list:
        if isinstance(element, list):
            result.extend(flatten_list(element))
        else:
            result.append(element)
    return result

# Test cases
assert flatten_list([0, 10, [20, 30], 40, 50, [60, 70, 80], [90, 100, 110, 120]]) == [0, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120]
assert flatten_list([[10, 20], [40], [30, 56, 25], [10, 20], [33], [40]]) == [10, 20, 40, 30, 56, 25, 10, 20, 33, 40]
assert flatten_list([[1,2,3], [4,5,6], [10,11,12], [7,8,9]]) == [1,2 ,3 ,4 ,5 ,6 ,10 ,11 ,12 ,7 ,8 ,9]
```