Yu Qiuyu is a famous writer. Once, he went to Germany to learn more about the life there. He found a room for renting . The owner was an old man. Yu looked around the room and found it very nice, so he decided to rent it. The old man smiled, saying, "Don't worry, young man. You haven't lived here. I think you can try living here for a few days. Then you can decide whether to live for a long time or not."  Yu thought it fair enough, and finally signed a contract  of five days. The room was quite comfortable. The cleaners took away the trash every day. The hallway was always tidy and clean. On the fifth day, when Yu wanted to talk with the old man about the long-time rent, he broke a glass carelessly. He was very nervous, feeling that the glass was expensive. However, when he told the old man on the phone, the old man said , "Don't worry. It's not a big deal. I'll bring one later." Yu swept the glass pieces into the trash bag together with other things, and put them outside of the door. A moment later, the old man came. After entering the room, he asked before Yu said anything, "Then where are the glass pieces?" Yu answered quickly, "I put them outside." The old man went out at once. After looking at the trash bag, he came back to the room with a _ face. He said to Yu, "You can move out tomorrow, because I won't rent the room to you." Yu couldn't believe his ears and asked, "Is it because I broke your favorite glass that you are upset?" "No, it's because you didn't think of others." Just then, the old man went out of the room with a pen and another trash bag. He poured out the trash that Yu had put in the bag. Then the old man picked up every piece of glass very carefully. After a long time, he put all the glass pieces into a trash bag, and wrote with the pen on the bag: "Dangerous! Glass pieces inside". And other trash was put into another bag, with "Safe" written on it. Yu was looking at it. He didn't know what to say. His face burned with shame. According to the writer, the old man refused to rent the room because  _  .
Yu didn't know how to throw away trash he didn't think Yu could make the room clean he didn't think Yu cared about others a lot Yu didn't tell him about the broken glass