Domino construction uses a. vertical steel support and horizontal slab of reinforced concrete which is connected by stairways. b. a horizontal beam that extends past its vertical support. c. suspension cables which are suspended from vertical supports anchored into the ground or a riverbed. d. one or more triangular units that are connected at the joints by long beams.

The gregorian chant was a major cultural milestone in the middle ages. it was one of the first codified forms of music meant to be played as written, where previously it was difficult to mass-produce and disseminate any music. what's more, these chants were also some of the first examples of musical notation: the notes and bars of today's music sheets are a reflection of centuries of evolution beginning with these chants. it became official throughout the entirety of the catholic church, meaning that nearly all of europe followed this musical notation and styling.