并从用户文本中返回两个重复次数最多的字母

def find_most_common_letters(text):
    letter_count = {}
    for letter in text:
        if letter.isalpha():
            if letter in letter_count:
                letter_count[letter] += 1
            else:
                letter_count[letter] = 1
    
    sorted_letters = sorted(letter_count.items(), key=lambda x: x[1], reverse=True)
    most_common_letters = [letter[0] for letter in sorted_letters[:2]]
    
    return most_common_letters

# 示例用法
text = "This is a sample text."
result = find_most_common_letters(text)
print(result)