------
## 最终结论
```python
def check_if_last_char_is_a_letter(txt):
    if not txt:
        return False
    txt = txt.strip()
    if txt and txt[-1].isalpha():
        words = txt.split()
        if len(words) > 0 and len(words[-1]) == 1:
            return True
    return False
```