1 2 3 4 1 _ _ _ _ 2 _ _ _ _ 3 _ _ _ _ 4 _ _ _ _ ACROSS 1) a written agreement between two states or sovereigns 2) a person who makes use of a thing; someone who uses or employs something 3) the world's longest river (4150 miles); flows northward through eastern africa into the mediterranean; the ____ river valley in egypt was the site of the world's first great civilization 4) united states virologist who developed the ____ vaccine that is injected against poliomyelitis (born 1914) DOWN 1) a humorous play on words 2) the largest continent with 60% of the earth's population; it is joined to europe on the west to form eur____; it is the site of some of the world's earliest civilizations 3) any small compartment 4) a journey by ox wagon (especially an organized migration by a group of settlers) ** Scroll down for solution. ** Are you sure you want to peek? pact user nile salk