Usted- to say formal "you"
Ve hacer la tarea.
Tienes que ir a tu cuarto.
Tienes que ser respetuoso.
Pues claro que si parce el sistema nervioso pertenece a la espinal
In railway signalling, an interlocking is an arrangement of signal apparatus that prevents conflicting movements through an arrangement of tracks such as junctions or crossings. The signalling appliances and tracks are sometimes collectively referred to as an interlocking plant. An interlocking is designed so that it is impossible to display a signal to proceed unless the route to be used is proven safe.
