isalpha函數是用來檢查字符串中的字符是否都是字母，如果是則返回True，否則返回False。正確使用isalpha函數進行字符串檢查的方法如下：
import string
s = "HelloWorld"
if s.isalpha():
print("All characters are letters")
else:
print("There are non-letter characters")
這段代碼會輸出"All characters are letters"，因為字符串s中的所有字符都是字母。
s = "Hello, World!"
all_letters = True
for char in s:
if not char.isalpha():
all_letters = False
break
if all_letters:
print("All characters are letters")
else:
print("There are non-letter characters")
這段代碼會輸出"There are non-letter characters"，因為字符串s中包含非字母字符。
