【简答题】B If you thought pilots dimmed (调暗) the lights before takeoff to give you some shuteye, think again. Believe it or not, the dim lighting could actually help save your life in case of a plane emergency...
【简答题】An elevator lowers you into the world of Carlsbad Cavern, the big cave at Carlsbad Caverns National Park. Silent, except for the voices of guides and visitors. And not completely dark. The ____6____ h...