(3)润写一个程序(类),用户输入一段英文,然后输出这段英文中所有长度为3个字母的单词井且如果单词如果有连续 复了2次,只输出一个【例: This isis a desk,程序输出 his is a desk】,(提示,有re正则匹配来做)

import re
x = input('Please input a string:')
pattern = re.compile(r'\b[a-zA-Z]{3}\b')
print(pattern.findall(x))