托福tpo23综合写作及原文材料1 Inthelecture,theprofessorpointsoutthatthehypothesismadebythereadingpassageisnota下面是小编为大家整理的2023托福tpo23综合写作及原文材料,菁选2篇,供大家参考。
托福tpo23综合写作及原文材料1
In the lecture, the professor points out that the hypothesis made by the reading passage is not adequate to explain why the population of Yellow Cedar is on the
decline. He points out several weaknesses of the statements made by the reading passage.
On one hand, the professor claims that insect parasite may not be the fundamental cause of the decline. In fact, he argues that healthy yellow cedar can secrete chemicals which can kill the cedar bark beetles so that they are unlikely to suffer from insect parasite. The trees that suffers insect parasite have already been sick or on the edge of death.
On the other hand, the professor asserts that brown bears cannot cause overall decline in yellow cedar population. There is decline both on the mainland of North America and islands along the coast. However, there is no brown bear on the islands at all.
What’s more, the professor doubts the hypothesis that the change of climate is to blame for the declination. He admits that the climate has changed rapidly recently. And, if the climate change is the real cause, the number of trees died on the higher elevation should be larger than that on a lower elevation. The fact is, however, on the opposite.
托福tpo23综合写作及原文材料2
Populations of the yellow cedar, a species of tree that is common in northwestern North America, have been steadily declining for more than a century now, since about 1880. Scientists have advanced several hypotheses to explain this decline.
黄杉是北美西北部常见的树木。但是从 1880 年开始的一个多世纪以来，黄杉的
数量在逐渐减少。目前，科学家提出了几个假说来解释黄杉数量的下降。
One hypothesis is that the yellow cedar decline may be caused by insect parasites, specifically the cedar bark beetle. This beetle is known to attack cedar trees; the beetle larvae eat the wood. There have been recorded instances of sustained beetle attacks overwhelming and killing yellow cedars, so this insect is a good candidate for the cause of the tree’s decline.
其中一个假说认为黄杉数量下降是由以衫皮甲虫为代表的寄生害虫导致。这种甲 虫据了解是以杉树皮为食，而其幼虫则以木质部分为食。史上不乏对于甲虫侵蚀 和导致黄杉大量死亡的记录。因为，这种甲虫很可能是黄杉数量减少的原因。
A second hypothesis attributes the decline to brown bears. Bears sometimes claw at the cedars in order to eat the tree bark, which has a high sugar content. In fact, the cedar bark can contain as much sugar as the wild berries that are a staple of the bears’ diet. Although the bears’ clawing is unlikely to destroy trees by itself, their aggressive feeding habits may critically weaken enough trees to be responsible for the decline.
第二种假说认为是棕熊导致了黄杉数量的减少。熊有时会扒下黄杉的树皮用以食 用，因为黄杉树皮还有很高的糖分。事实上，黄杉树皮的含糖量同棕熊主要使用 的野生浆果相差无几。虽然棕熊扒树皮的行为不会直接导致黄杉的死亡，但是它 们这种破坏性的觅食行为却因为降低了树木的生命力，而间接导致黄杉数量的.减 少。
The third hypothesis states that gradual changes of climate may be to blame. Over the last hundred years, the patterns of seasonal as well as day-‐to-‐day temperatures have changed in northwestern North America. These changes have
affected the root systems of the yellow cedar trees: the fine surface roots now start growing in the late winter rather than in the early spring. The change in the timing of root growth may have significant consequences. Growing roots are sensitive and are therefore likely to suffer damage from partial freezing on cold winter nights. This frozen root damage may be capable of undermining the health of the whole tree, eventually killing it.
第三个假说是气候的缓慢变化导致了黄杉数量的减少。在过去的一百年里，在北 美西北部，无论是季节性的气候更替还是每天的气温调节都发生了变化。这些变 化对黄杉根系产生了影响。以前，黄杉的表面细根是初春开始生长的;而现在却 在晚冬就开始生长。根系生长时间的变化可能会造成非常严重的后果。新生的根 系都非常敏感，因而非常容易因为冬季夜晚部分结冰的温度受到损害。这种根系 冻伤现象可能会导致整个树木健康状况下降，并逐渐导致死亡。
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