One day, Jack came to Mike's house and said , "Mike, you have so many good books. Can you lend me a book to read?" Mike didn't want to lend a book to his friend, and he said, "Why do you want to take my book home? You can read it here in my house." Jack found that his friend was very selfish, but he said nothing. The next day, Mike came to Jack's house and said, " Jack , you have a good garden-knife, I want to work in my garden tomorrow. Can I use it for two days?" Jack answered, "Why do you want to take my garden knife home? You can work with it in my garden." Mike is   _  .
a kind boy Jack's girlfriend a selfish girl selfish