11-15為題組
       In 1997 Los Angeles experienced a massive power blackout following anearthquake. The entire city was thrown into __11__ . The emergency call service, 911,was overwhelmed with panicked residents reporting “a giant silvery cloud” in the sky.The callers did not realize that they were seeing the Milky Way, the galaxy __12__ oursolar system, in the night sky for the first time. Some of these city people had neverbefore experienced a sky unpolluted by light.
       Light pollution results from excessive light produced by humans at night. One ofthe most common __13__ of light pollution is sky glow. It refers to the brightening ofthe night sky __14__ artificial sources, mainly electric lights from houses, offices,factories, cars, streetlamps, billboards, and buildings, turning night into day for peoplewho work and play long after sunset. People living in cities with high levels of skyglow have __15__ seeing more than a handful of stars at night. Up to 80% of theworld’s population now lives under light-polluted skies, meaning a third of humanitycan no longer see the Milky Way.
【題組】11.
(A) pieces
(B) darkness
(C) worries
(D) stillness