The unicameral legislative branch created by the articles of confederation was most likely changed to a bicameral branch in the united states constitution because people

The answer is:  They wanted more of a separation of government power.

In unicameral legislative branch, there is only one chamber that held the full control regarding the type of legislation that can be passed by the government. Creating bicameral branch on the other hand, would create more than one oppositions that limit each other's influence within the government.

first, the romans stayed isolated because they had to defend their own territories from neighboring cities that were harassing them, like the etruscans. second, once the romans managed to defeat their neighbors, and started to expand their territory, they started to build roads and bridges. finally, now that the romans have covered their territory with roads functioning as highways, they could mobilize their legions faster to assemble larger military units in a specific place