A collapse icon means indicates that the folder is expanded and its subfolders are listed below the folder name.
Plus sign
plus sign
A high on a weather map indicates a high pressure area. This indicates a new weather front is moving into that area.
B
Blue
because of the increace in industry in the area and the need for slave labour.
Darius the Great.
The exponent indicates how many spaces to move the decimal point to the right (+) or to the left (-) when expanded.
The Persian Empire was established and expanded to its greatest area.
Cubic indicates an area while the 1mm indicates a distance so they don't equate.
It is impossible to answer as the boundary of London is not precise. The metropolitan area has expanded.