Determining the hemisphere is easy: latitude zones a, C, d, e, F, g, h, J, K, l, and m are in the Southern hemisphere, and the rest are in the Northern hemisphere.
这种确定非常简单：纬度区a、C、D、E、F、G、H、J、K、L和m位于南半球，而其余区位于北半球。
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The Romans had to keep on cooking up new letters every time their numbers got bigger - C for 100, D for 500, M for 1, 000 - because they didn't have zeros to add on to the end.