The armies of ancient Rome often had to cross rivers to reach distant parts of the empire. This posed a problem because bridges built by earlier civilizations could not bear the weight of many troops. The Romans overcame this obstacle by building

the answers is b.   environments.

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the colonists were also expected to pay a tax to meet the costs of establishing and manning the borders of the proclamation line which led to the belief that the king had sided with the indians despite pontiac's rebellion, against the interests of the settlers. this contributed to the causes of the american revolution.

i would have to say i believe that it is a.