对于准备考托福的同学来说，不知道准备得怎么样呢？今天就和出国留学网的小编一起来看看TPO阅读中有哪些托福写作可以借鉴的表原因的表达？
说理在写作中必不可少，而因果逻辑关系又是说理中不可或缺的。我们一直强调托福各单项的备考不是孤立的，托福阅读中的很多内容可以有效帮助我们提升托福写作，下面小站君汇总了 TPO 中常用的表示原因的一些表达，防止大家一个 because 一用到底。大家有几个替换就行，不用搞的太多，多了也记不住。记得时候最好以句子为单位来记，效率高一些。另外托福写作水平的提升重在练习，因此除了识记大家还需要注意合理仿写应用。
result from
In general， it is believed that these two extinctions resulted from drastic environmental changes that followed meteorite impacts or massive volcanic eruptions. [TPO 15-2-1]
总体来说，这两次灭绝被认为是陨石撞击或者大规模的火山爆发导致的剧烈的环境变化造成的。
In general， it is believed that X results from A.
result primarily or mainly or largely from
The growth of independent guilds was furthered by the fact that surplus was not a result of domestic craft production but resulted primarily from international trading；
独立行会不断增加，是因为剩余价值的产生并非由于国内生产，而是主要来自于国际间的贸易活动。
X is not a result of A but results primarily from B.
one of the most likely causes for
Evidence points to hunting by humans and habitat destruction as the likely causes for the current mass extinction. [TPO 15-2-3]
但有证据指出，人类狩猎以及破坏栖息地很可能是当前大规模物种灭绝的原因。
Sb. points to A and B as the likely causes of X.
the explanation may be that
The explanation may be that the terrestrial planets were once much larger and richer in these materials but eventually lost them because of these bodies’ relative closeness to the Sun， which meant that their temperatures were relatively high. [TPO 16-3-6]
有一种解释认为，类地行星曾经体积更大并且物质构成上更为丰富多样，但因为它们距太阳较近致使温度相对较高而最终失去这些物质。
the most obvious reason for sb to do sth is that
Few have directly questioned what might lead a teacher to want to become reflective. Apparently， the most obvious reason for teachers to work toward reflective practice is that teacher educators think it is a good thing. [TPO 9-2-6]
很少人直接质疑什么可能让一个教师想变成反思型教师。显然，使教师朝着反思行为努力的最直接的原因是师资培训者认为这是一件很好的事情。
Few have directly questioned what might lead sb. to do X. Apparently， the most obvious reason for sb. to do X is that A.
partly due to
This has been so since ancient times， partly due to the geology of the area， which is mostly limestone and sandstone， with few deposits of metallic ore and other useful materials. Ancient demands for obsidian （a black volcanic rock useful for making mirrors and tools） led to trade with Armenia to the north， while jade for cutting tools was brought from Turkistan， and the precious stone lapis lazuli was imported from Afghanistan. [TPO 16-1-1]
这种情况（贸易是主要支柱）从古至今都是如此，一部分原因是中东地区的地质环境——多为沙石和石灰岩，金属矿藏和其它有用材料很少。古代对黑曜石（一种火山岩，可以用来制作镜子和工具）的需求引发了（中东地区）与北方的亚美尼亚之间的贸易；用作切削工具的玉石从土耳其斯坦购买；而贵重的琉璃青金石是从阿富汗地区进口。
Such anomalies are due to the relative abundance of the “isotopes” or varieties of each element.
出现这种反常现象，主要是因为相对丰富的“同位素”或者各种元素的多样性。
because
Because there is no space in the periodic table between these two elements， Mendeleyev suggested that the atomic mass of indium be changed to a completely different value， where it would fill an empty space between cadmium and tin.
但是因为在周期表中这两个元素之间没有缝隙，由此门捷列夫提出铟的原子质量变为截然不同的一个值，这样就可以将其置于镉和锡之间的空位。
Also， because the molecular motion of a gas depends on temperature， at the low temperatures of the Jovian planets even the lightest gases are unlikely to acquire the speed needed to escape. [TPO 16-3-5]
同时又因为气体分子运动取决于温度，所以在类木行星这样的低温环境下，即使是最轻的气体也无法达到所需要的逃逸速度。
Pluto is not included in either category， because its great distance from Earth and its small size make this planet’s true nature a mystery. [TPO 16-3-2]
冥王星不属于这两类中的任何一个，因为它距地球很远且体积较小，所以目前冥王星的真实形态仍然是个谜。
because of
The Jovian planets， because of their greater masses and thus higher surface gravities， have higher escape velocities （21-60 kilometers per second） than the terrestrial planets. [TPO 16-3-5]
由于类木行星的质量较大并因此产生更高的表面引力，因此，类木行星的逃逸速度（21～60千米/秒）要比类地行星高得多。
be responsible for
Variations in the composition of the planets are largely responsible for the density differences. [TPO 16-3-4]
行星的构成成分不同很大程度上是因为密度差异。
account for
Of the various hypotheses attempting to account for the late Cretaceous extinctions， the one that has attracted the most attention in recent years is the asteroid-impact hypothesis first suggested by Luis and Walter Alvarez. [TPO 15-2-5]
各种假说都试图对白垩纪时期后期物种灭绝做出解释，近年来Luis 和Walter Alvarez最先提出的小行星撞击假说备受人们关注。
Of the various reasons attempting to account for X， the one that has attracted the most attention is A.
which explain why
The disadvantage of using waterpower is that streams do not necessarily flow in places that are the most suitable for factories， which explains why so many water-powered grain and textile mills were located in undesirable places. [6-1-1]
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