根据句子意思及汉语提示,写出所缺的单词。
1. Oh, I have ▲ (忘) my key in the room, we can’t open the door.
2. Though he lives alone, he has a lot of friends and doesn’t feel ▲ (孤独的) .
3. Mrs. White smiled ▲ (幸福地) when she received a present from her daughter on Mother’s Day.
4. As we all have grown up, we should learn to look after ▲ (自己).
5. Everybody knows the ▲ (重要性) of doing exercises, but few can keep doing it.