letter_frequency = get_letter_frequency(cipher_text.lower()) sorted_letters = sorted(letter_frequency.keys(), key=lambda x: letter_frequency[x], reverse=True)将频率为0的字母排除出字典，并输出被排除的字母

可以将代码修改为：

letter_frequency = get_letter_frequency(cipher_text.lower())
excluded_letters = [letter for letter in letter_frequency.keys() if letter_frequency[letter] == 0]
sorted_letters = sorted([letter for letter in letter_frequency.keys() if letter_frequency[letter] > 0], key=lambda x: letter_frequency[x], reverse=True)
print("Excluded letters:", excluded_letters)

这样就可以排除字频为0的字母，并输出被排除的字母了。