you might try
"each greek city-state or colony was affected by the fact that greece was a peninsula ,and surrounded by water on three sides"
But without more context, it's hard to say what they're looking for...
Hello, Bob and welcome!
For the first blank, I'd use 'polis' and I'd also use 'peninsula' for the second fill in:
"Each Greek city-state or polis was affected by the fact that Greece was a peninsula, and surrounded by water on three sides."
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