Ⅰ.阅读理解
Even if trees cannot walk, they are still on the move.
In parts of the Arctic, entire forests are moving northward.Across the Arctic, temperatures are rising faster than anywhere else in the world.As that happens, the tree line that marks where forests stop and the treeless tundra(冻土地带) starts has been shifting northward.Trees growing along the tree line must protect themselves from the cold wind.To do this,_plants tend to grow horizontal(水平的) branches low to the ground.The energy it takes for trees to grow this way means they don't have enough energy to make seeds.
But as Earth's climate has been warming, trees no longer have to just grow horizontally.Many can instead grow up, toward the sky.This takes less energy.And with all that leftover energy, these trees have started producing more seeds.This happens especially in places where the white spruce(白云杉) grows.
White spruce, which is a North American tree, is quite able to produce a lot of seeds, which can move long distances in the wind.When wind－blown seeds end up on the tundra beyond the tree line, they eventually can sprout(发芽) new trees.This explains how a forest can move.Of course, the process would work only if the tundra were warm enough.But in recent years, the whole planet has been warming.
New trees will provide shelters for some snow, keeping the sun's rays from making the white surface disappear.Instead, the trees absorb the sun's heat.This warms the surrounding air.The extra warmth encourages even more trees to produce seeds.That further boosts a forest's ability to expand.In addition, more trees will trap more snow, preventing much of it from being blown away.Snow can trap heat in the soil below, which encourages trees to grow.The recent rise of temperature has helped more trees grow past the tree line.People worry about impacts on the animals that depend on frozen conditions for food and shelter.
本文是一篇报道，主要报道了由于气温升高，北极部分地区的森林正在向北移动的事件及原因。
1．What is the main cause of the trees in the Arctic moving northward?
A．The shrinking of northern tundra.
B．The rising temperature.
C．The fierce and cold wind.
D．The abundant resources in the north.
答案：B
解析：细节理解题。根据第二段第二、三句“Across the Arctic, temperatures are rising faster than anywhere else in the world. As that happens, the tree line that marks where forests stop and the treeless tundra (冻土地带) starts has been shifting northward.”可知，森林向北移动的原因是气温上升。故答案选B。
2．What does the underlined word “this” in Paragraph 2 mean?
A．To produce more seeds.
B．To move northward.
C．To respond to the climate change.
D．To protect themselves from the cold wind.
答案：D
解析：代词指代题。根据第二段第四、五句“Trees growing along the tree line must protect themselves from the cold wind. To do this,_plants...”可知，此处的this指代前面的“protect themselves from the cold wind”，即树木保护自己免受冷风侵袭。故答案选D。
3．What can be inferred from the last paragraph?
A．New trees can trap the snow, which may make the soil colder.
B．The trapped snow prevents new trees from producing more seeds.
C．New trees can make the surrounding air warmer.
D．New trees can bring more food and shelter for local animals.
答案：C
解析：推理判断题。根据最后一段第二、三句“Instead, the trees absorb the sun's heat. This warms the surrounding air.”可知，树能吸收太阳的热量，使周围的空气变得暖和。由此可知，新生长出来的树能够吸收更多的热量，使周围的空气更温暖。故答案选C。
4．The passage is most probably taken from ______.
A．a science report B．a health report
C．a fashion magazine D．a children's magazine
答案：A
解析：推理判断题。A项意为“科学报道”；B项意为“健康报道”；C项意为“时尚杂志”；D项意为“儿童杂志”。通读全文可知，本文主要介绍了由于气温升高，北极部分地区的森林正在向北移动的事件。由此可推知，本文应选自科学报道。故答案选A。
