1 .		Some geysers have regular schedules, while others cannot be predicted as _____.
2 .		Immense heat lurks _____ below the surface of geysers and boiling hot springs.
3 .		Some tourists have behaved _____, throwing trash into the geysers and choking them off.
4 .		The geological forces at work in Yellowstone are understood fairly _____ by scientists.
5 .		However, _____ studies are needed before we will understand the tourists.
Answer choices in this exercise are randomized and will appear in a different order each time the page is loaded.