单词on-one-s-back
fall on one"s back.
面朝天摔倒。
The pose that sleep in order to lie on one"s back best, lest sideways squashs breast.
睡觉的姿势以仰卧最好，以免侧身挤压乳房。
Take a thing on one"s back
把一物背到背上
carry a bag on one"s back [shoulders]
背袋子于背[肩]上
lie on one"s back; lie supine
仰卧；睡卧
Ride a child on one"s back
让孩子骑在背上
Fall flat on one"s back
摔个仰八叉
wear sth on one"s back
背着某物