At the 1939 World's Fair, the Sawyer company introduced which stereo slide viewer that gives 3-D views?

At the 1924 Olympics, which future movie Tarzan won the 100-meter freestyle in under a minute? At the 1936 Olympics, who ran an Olympic-record 20.7 seconds to win the 200 meters? At the 1939 New York World's Fair, the Borden exhibit featured a live version of which trademarked cow? At the 1939 World's Fair, the Carrier Corporation demonstrated air conditioning in an imitation of which domed dwelling? At the 1942 Battle of El Alamein, Bernard Montgomery defeated which German commander, nicknamed "the Desert Fox"? At the 1953 Paris Motor Show, which famed Porsche model debuted? At the 1968 Democratic convention, which future NAACP chairman was briefly put forward for vice president? At the 1972 Munich Olympics, who swam in seven events, including relays, and won them all in world-record times?