single tubing wellhead

例句：

1. 1. Thesingle tree in the park is a symbolof peace.
   公园里那棵孤立的树是和平的象征。
2. 2. She prefers tolive alone rather than with others.
   她宁愿独自生活，也不愿与他人为伴。
3. 3.He has only one friend in the world.
   他世上只有一个朋友。