------
## 最终结论
```python
def add_string(lst, string_format):
    return [string_format.format(item) for item in lst]

# Test cases
assert add_string([1,2,3,4],'temp{0}') == ['temp1', 'temp2', 'temp3', 'temp4']
assert add_string(['a','b','c','d'], 'python{0}') == ['pythona', 'pythonb', 'pythonc', 'pythond']
assert add_string([5,6,7,8],'string{0}') == ['string5', 'string6', 'string7', 'string8']
```