reverse flow zone
71Chernobyl disaster — This article is about the 1986 nuclear plant accident in Ukraine. For other uses, see Chernobyl (disambiguation). Chernobyl disaster …
72Water resources — A natural wetland Water resources are sources of water that are useful or potentially useful. Uses of water include agricultural, industrial …
73Russia — /rush euh/, n. 1. Also called Russian Empire. Russian, Rossiya. a former empire in E Europe and N and W Asia: overthrown by the Russian Revolution 1917. Cap.: St. Petersburg (1703 1917). 2. See Union of Soviet Socialist Republics. 3. See Russian… …
74oxidation–reduction reaction — ▪ chemical reaction Introduction also called redox reaction any chemical reaction in which the oxidation number of a participating chemical species changes. The term covers a large and diverse body of processes. Many oxidation– reduction… …
75pre-Columbian civilizations — Introduction the aboriginal American Indian (Mesoamerican Indian) cultures that evolved in Meso America (part of Mexico and Central America) and the Andean region (western South America) prior to Spanish exploration and conquest in the 16th …
76ARAB WORLD, 1945–2006 — The Arab world is divided into four subregions: the Maghreb (morocco , tunisia , algeria , libya , Mauritania), the Nile Valley (egypt and Sudan), the Fertile Crescent (syria , lebanon , iraq , jordan , and the palestinian authority ), and the… …
77cañada — /keuhn yah deuh, yad euh/, n. Chiefly Western U.S. 1. a dry riverbed. 2. a small, deep canyon. [1840 50; < Sp, equiv. to cañ(a) CANE + ada n. suffix] * * * Canada Introduction Canada Background: A land of vast distances and rich natural resources …
78Canada — /kan euh deuh/, n. a nation in N North America: a member of the Commonwealth of Nations. 29,123,194; 3,690,410 sq. mi. (9,558,160 sq. km). Cap.: Ottawa. * * * Canada Introduction Canada Background: A land of vast distances and rich natural… …
79printing — /prin ting/, n. 1. the art, process, or business of producing books, newspapers, etc., by impression from movable types, plates, etc. 2. the act of a person or thing that prints. 3. words, symbols, etc., in printed form. 4. printed material. 5.… …
80volcano — /vol kay noh/, n., pl. volcanoes, volcanos. 1. a vent in the earth s crust through which lava, steam, ashes, etc., are expelled, either continuously or at irregular intervals. 2. a mountain or hill, usually having a cuplike crater at the summit,… …
