TPO 1-10 细节题汇总.doc

TPO_1-10_细节题汇总TPO-1-1
Paragraph 1:The transition from forest to treeless tundra on a mountain slope is often a dramatic one. Within a vertical distance of just a few tens of meters, trees disappear as a life-form and are replaced by low shrubs, herbs, and grasses. This rapid zone of transition is called the upper timberline or tree line. In many semiarid areas there is also a lower timberline where the forest passes into steppe or desert at its lower edge, usually because of a lack of moisture.
2. Where is the lower timberline mentioned in paragraph 1 likely to be found?
In an area that has little water
In an area that has little sunlight
Above a transition area
On a mountain that has on upper timberline.
Paragraph 2:The upper timberline, like the snow line, is highest in the tropics and lowest in the Polar Regions. It ranges from sea level in the Polar Regions to 4,500 meters in the dry subtropics and 3,500-4,500 meters in the moist tropics. Timberline trees are normally evergreens, suggesting that these have some advantage over deciduous trees (those that lose their leaves) in the extreme environments of the upper timberline. There are some areas, however, where broadleaf deciduous trees form the timberline. Species of birch, for example, may occur at the timberline in parts of the Himalayas.
4. Paragraph 2 supports which of the following statements about deciduous trees?
They cannot grow in cold climates.
They do not exist at the upper timberline.
They are less likely than evergreens to survive at the upper timberline.
They do not require as much moisture as evergreens do.
Paragraph 3:At the upper timberline the trees begin to e twisted and deformed. This is particularly true for trees in the middle and upper latitudes, which tend to attain greater heights on ridges, whereas in the tropics the trees reach their greater heights in the valleys. This is because middle- and upper- latitude timberlines are strongly influenced by the duration and depth of the snow cove