题目

Climate is the average weather usually taken over a 30-year time period for a particular region and time period. Climate is not the same as weather, but rather, it is the average pattern of weather for a particular region. Weather describes the short-term state of the atmosphere (大气).The climate is changing. Many agreed that climate change may be one of the greatest threats (威胁) facing the planet. Recent years show increasing temperatures in various regions, and/or increasing extremities (极端性) in weather patterns.Is the Earth getting warmer? Yes! The Earth has warmed by about 1°— You've dropped            "s'' in the word "acros''. — Oh,            letter "s'' should be doubled like this "across''. [     ]A. a, aB. an, a C. an, the D. the, the