Dutch elm disease devastated which North American tree, once a favorite for lining city streets?

Which Cleveland businessman founded Standard Oil in 1870 and retired from active management in the 1890s? Complete the title of John Keats' 1819 ballad: "La Belle Dame sans ___." In a famous 1936-37 sit-down strike in Flint, Michigan, the United Auto Workers took on which company? Norse settlers began arriving around 874 on which North Atlantic island, which founded its Althing parliament in 930? While living in the U.S., which scientist was offered the presidency of Israel in 1952? By tradition, no pope ever chooses which name? By weight, about 65 percent of the human body is which element? Which nomadic desert people of the Middle East are famed for breeding Arabian horses?