single lift dobby

例句：

1. 1. Thesingle tree in the park is a symbolof peace.
   公园里那棵单独的树是和平的象征。
2. 2. She has only onefriend in the whole world.
   她全世界只有一个朋友。
3. 3. He lives alone in a small house.
   他独自住在一间小房子里。