Complete the text with suitable prepositions.
Fires swept (a) ______the prairies at any time (b) ______practically ten months of the year, although the worst were usually (c) ______the fall, (d) ______the grass standing high and rich (e) ______oily seeds. The prairie fires could be set (f) ______lightning and by the carelessness (g) ______greenhorns in the country. Once started, the heat of the fire created a high wind that could sweep it (h) ______a hundred miles of prairie in an incredibly short time. Settlers soon learned to watch the horizon (i) ______the curling smoke rising (j) ______prairie grass.