Read the following passage and mark the letter A, B, C or D on your answer sheet to choose the word or phrase that best fits each other numbered blanks. 

     As Earth’s climate has warmed, a new pattern of more frequent and more intense weather events has unfolded around the world. Scientists identify these extreme weather events based on the historical (39) ________ of weather in a particular region. They consider extreme weather events to be those (40) _______ produce unusually high or low levels of rain or snow, temperature, wind, or (41) _______ effects. Typically, these events are considered extreme if they are unlike 90% or 95% of similar weather events that happened before in that same area. 

     A warmer and more moist atmosphere over the oceans makes it likely that the strongest hurricanes will be more intense, produce more rainfall, and possibly be larger. In addition, global warming causes sea level to (42) _________, which increases the amount of seawater, along with more rainfall, that is pushed on to shore during coastal storms. That seawater, along with more rainfall, can result in destructive flooding. (43) ______ global warming is likely making hurricanes more intense, scientists don't know yet if global warming is increasing the number of hurricanes each year. The effect of global warming on the frequency, intensity, size, and speed of hurricanes remains a subject of scientific research.

Read the following passage and mark the letter A, B, C or D on you answer sheet to indicate the correct answer to each of the questions. 

      Glaciers are large masses of ice on land that show evidence of past or present movement. They grow by the gradual transformation of snow into glacier ice. A fresh snowfall is a fluffy mass of loosely packed snowflakes, small delicate ice crystals grown in the atmosphere. As the snow ages on the ground for weeks or months, the crystals shrink and become more compact to form firm, a much whole mass becomes squeezed together into a more dense form, granular snow. As new snow falls and buries the older snow, the layers of granular snow further compact to form firm, a much denser kind of snow, usually a year or more old, which has little pore space. Further burial and slow cementation- a process by which crystals become bound together in a mosaic of intergrown ice crystals- finally produce solid glacial ice. In this process of recrystallization, the growth of new crystals at the expense of old ones, the percentage of air is reduced from about 90 percent for snowflakes to less than 20 percent for glacier ice. The whole process may take as little as a few years, but more likely ten or twenty years or longer. The snow is usually many meters deep by the time the lower layers are converted into ice. 

      In cold glaciers those formed in the coldest regions of the Earth, the entire mass of ice is at temperatures below the melting point and no free water exists. In temperate glaciers, the ice is at the melting point at every pressure level within the glaciers, and free water is present as small drops or as larger accumulations, in tunnels within or beneath the ice. Formation of a glacier is complete when ice has accumulated to a thickness (and thus weight) sufficient to make it move slowly under pressure, in much the same way that solid rock deep within the Earth can change shape without breaking. Once that point is reached, the ice flows downhill, either as a tongue of ice filling a valley or as thick ice cap that flows out in directions from the highest central area where the most snow accumulates. The up down leads to the eventual melting of ice. 

 Which of the following does the passage mainly discuss?

Mark the letter A, B, C, or D on your answer sheet to indicate the sentence that best completes the following exchanges.