without any other people 单独地，独自地
1. She’s afraid of going out alone at night.
2. He was left alone, with no one to look after him.
3. She lives all alone in that large house.
sad and unhappy, without any friends 孤单的，单独的，独自一人的
1. I’v been so alone since you went away.
2. She watches TV when she is alone.
3. I don’t feel secure when I’m alone in the house.
unhappy because you have no friends or people to talk to 寂寞的，孤独的，孤寂的
1. He felt lonely without his wife and children.
2. She feels rather lonely in the strange town.
3. He was very lonely at first when he moved to London.