n.

1. 支持
2. 逆行
3. 里衬
4. 背脊

n.

1. material or moral support.
2. a layer of material that forms, protects, or strengthens the back of something.
3. (especially in popular music) musical or vocal accompaniment to the main singer or soloist.
4. Phonetics  the movement of the place of formation of a sound towards the back of the mouth.