快速整齐地检查字符串是否只包含字母表，而不考虑字符集？

import re

def check_alphabet(string):
    pattern = r'^[a-zA-Z]+$'
    if re.match(pattern, string):
        return True
    else:
        return False

print(check_alphabet("Hello"))  # True
print(check_alphabet("Hello123"))  # False
print(check_alphabet("123"))  # False