When they invented concrete. Roman concrete set underwater and was used to build harbours.
New England was well suited for commerce because of good coastal harbors.
This reads like a test question or homework and you need to answer it. It is obvious that it based on readings you were assigned and given.
Baltimore, New York City, and Boston have harbors.
The Romans may or may not have invented the bath plug. They were certainly one of the first civilizations to develop indoor plumbing and use bath plugs.
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Because New Jersey didn't have any natural harbors.
to have more fresh water
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New England was well suited for commerce because of good coastal harbors.
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They played minecraft and designed them there
it has good terrain and climate, good for fishing
the Romans added to their own talents and tastes to what they learned from cultures.
Your grammar is a bit...ambiguous, but perhaps you mean "did Europe's navigable rivers and good natural harbors make trade difficult? If this is the case, then the answer is no. Rivers and harbors HELPED European trade. Goods could be moved up rivers or into natural harbors for docking, making trade easier.
This reads like a test question or homework and you need to answer it. It is obvious that it based on readings you were assigned and given.
Good coastal harbors
New England was well suited for commerce because of good coastal harbors.