lying on one's back
He is lying on his back.
Il était allongé sur le dos sur la plage.
He was lying on his back on the beach.
Il était allongé sur le dos sur le lit.
He was lying on his back on the bed.
I was lying on my back.
Allongé sur le dos il regardait le ciel.
Lying on his back he looked at the sky.
Was he lying on his back?
He was lying on his back.