What is a description of a truss bridge?

The Grand Canyon and the Pertrified forest are scenic areas in what state? What river is the longest river in Texas excluding boundaries? What is toughness in civil engineering? How many people died during the building of the Hoover Dam from carbon dioxide poisoning? What city was renamed Ho Chi Minh City? What land animal have scales in Singapore zoo? Are problems in lakes caused by acid rain solved by adding metal? How much does an 18 wheeler cost to go over the GW Bridge? Was the Erie Canal on schedule? What process were involved in creating dune's? Are there cactus in the Gobi desert? Do dandelions grow in forests? In witch ocean are there islands of Hawaii? What undersea volcanic formation that does not rise at least 1000 mater above the surrounding sea floor is called? What does one see at the Grevin Museum? Does Lake Michigan border Canada and the US? Why was crossing the Ohio river such an obstacle for many slaves? What colours make terracotta? Why do jellyfish die on beach? Can a desert exist in an ocean?