综合写作时态
在综合写作中，同学们都知道表示阅读、听力观点用一般现在时, 具体内容的时态跟阅读和听力中保持一致就可以。
但是在实际做题中，很多同学可能阅读/听力时没注意时态，或者发现原文中各种时态夹杂在一起，很迷糊。
所以，老师今天专门写了一篇推送，讲解给大家。
以下内容，已经加入托福写作团课程。
综合写作主要时态：一般现在时；一般过去时；完成时态；would表推测
以下例句来自TPO真题.
一. 一般现在时
表示客观存在/习惯性动作.
(1) 阅读、听力、写作中，表示观点，"认为、反驳、表明..." .
1. The professor/The writer believes/disagrees with it.
2. Unfortunately,each of the three theories about how agnostids lived has a serious weakness.
听力教授的观点，用现在时has。
3. A second reason to doubt that bees existed 200 million years ago is the absence of flowering plants in that period. (TPO45)
表示阅读观点，用is.
4. But this doesn't really prove that the smaller Caracas built in Brennan's time could do the same.
听力反驳观点，用prove.
(2). 表示”事实“（没有改变. 现在也这样)
A. 常出现在描述现在情况的文章。
比如：Tpo53，征收香烟税的好处
Many countries require cigarette smokers to pay particularly high taxes on their purchases of cigarettes; similar taxes are being considered for unhealthy foods. The policy of imposing high taxes on cigarettes and other unhealthy products has a number of social benefits.
本篇文章探讨的是现在很多国家征收香烟税，所以整篇文章主要都用现在时。
B. 如果是对已发掘、现在还存在的古代事物的解读，很多也用一般现在时。
⚠️ 常出现在历史谜团/考古话题等文章。
1. Some of those markings may resemble an old Irish alphabet, but many others do not. （TPO67: The supposed voyage of Brendan the Navigator ）
文章中提到的markings 虽然是考古发现的，但是resemble长得像是一直客观存在的，到现在也是，所以用一般现在时do not (resemble).
2. In 1912 a bookseller named Wilfrid M. Voynich acquired a beautifully illustrated handwritten book (manuscript) written on vellum (vellum is a material that was used for writing before the introduction of paper). The “Voynich manuscript,” as it became known, resembles manuscripts written in the fifteenth and sixteenth centuries. （TPO35: The Voynich manuscript）
虽然手稿是在1912年被获得的(acquired)。但是，目前还存在。同样，对他的一些客观性描述也可以用一般现在时。
(二) 过去时
表示动作发生在过去/现在已经不再存在.
常见于大多是历史、考古类话题中
1. Second, a team of researchers recently constructed a boat resembling a curragh. （TPO67）
船已经修建完成，所以用construct修建这个动作用过去时。
2. First, these sea cows were massive creatures—they were up to nine meters long and could weigh over ten tons—just enormous. (TPO34: The extinction of sea cows)
Sea cows已经灭绝了，所以对它的描述都用了过去时。
3. A little over 2,200 years ago, the Roman navy attacked the Greek port city of Syracuse. According to some ancient historians, the Greeks defended themselves with an ingenious weapon called a "burning mirror". (TPO30)
罗马海军是2200年前袭击的希腊，所以都用过去时。
4. First, the Native American site in Maine where the coin was discovered is located very far from other sites documenting a Norse presence in North America.(TPO44: 历史上的钱币)
钱币是之前考古发现discovered,所以用过去时。但这个地点，在地理位置上一直都距其他地方很远，是个普遍的现实，所以用is located.
(三). 现在完成时态: have/has done
表示发生在过去，但是动作一直延续到现在 or 动作的影响一直延续到现在。
1.In recent decades, global warming has contributed to the disappearance of many water and wetland habitats, causing entire species to go extinct. （ TPO48）
时间状语 in recent decades 表示最近的几十年，表明 全球变暖的影响确实从过去开始，一直延续到现在，所以用现在完成时。
2. A second problem is that no other coins have been found at the Canadian sites that were inhabited by the Norse. （TPOP44）
表示硬币一直到现在都还未被被发现。动作从过去延续到现在。
3. Several arguments have been made against powered flight. (TPO47)
表示一些理由已经被提出来了，但是这些理由的影响还持续到现在。
(四) would/ might…表示推测
⚠️ 高频难点
(1). would; might ...表示对将来情况的推测, “可能”。
也经常和if条件句连用，但是语气比will/may 委婉，可能性不如will.
1. Water from the lake would be pumped into the facilities and heated. (TPO54)
这篇文章提出3个方法来解决现在的问题。推测这3个方法可能的结果，所以用would be pumped.
2. Similarly, imagine how some consumers might react to higher taxes on unhealthy foods. They might continue buying the unhealthy foods they prefer even if they’re more expensive, and as a result have less money left to spend on healthy foods. (TPO53 听力)
推测一个对不健康食物征收高税这一政策可能引起的结果.
3. If precious metals are mined in large quantities, it would increase the supply of the metals, which could end up lowering their market price. （TPO52.）
推测移民小行星的可能性
(2). if did…, S+ would do sth.
对现在的虚拟/推测，即跟现在的情况相反。
多见于对现在事物有关的话题. 出现较少.
1. If laws prohibited the farmers from using harmful pesticides near sensitive frog populations, it would significantly reduce the harm pesticides cause to frogs. (TPO48: Declining frog populations)
这篇文章讲解的是如何解决青蛙减少的问题。if + prohibited, it + would reduce. 就是典型的对现在虚拟。 所以，这句话的实际意思是，法律没有禁止农民在对杀虫剂敏感的青蛙附近使用杀虫剂，所以杀虫剂对青蛙造成了很大的危害。
(3) would have done. 对过去的推测/假设：
常见考古类、历史类的文章
1. First, the written stories about Brendan’s voyage seem to make references to places his crew would have visited on the way to North America Sailors in Brendan’s time. （TPO67）
这篇文章讨论的是历史上是否Brendan 和他的船员真的到达过北美。阅读同意，听力反驳。这一句来自听力，表示对过去事件的推测.
2. The destruction of coastal and shallow-ocean species would have had a profound effect on food chains worldwide, leading to mass extinctions. (TPO39: Explanations of species extinction)
这篇分析的是历史上物种灭局的原因，是对过去事情的推测，所以用了would have done。表示， 沿海和浅海物种的毁灭将对全世界的食物链产生深远影响，导致大规模灭绝。
3. Pterosaurs that were as large as a giraffe were probably so heavy that they would not have been able to flap their wings fast enough to stay aloft for any length of time. (TPO47: Powered flight of Pterosaurs)
这篇分析的是已经灭绝的动物Pterosaurs的行为，对过去事情的推测，所以用woould not have been able to.
（五）: 现在和过去时间交叉
⚠️ ⚠️ 超高频难点
在很多历史/考古文章中，阅读/听力在论证观点的时候，常会用现在相似的事物/客观真理作为证据，来支持对过去事物的看法。时态就比较多变。尤其需要大家注意。
1. One theory involves(阅读观点，一般现在时) the decline of sea levels. Near the end of the Triassic period, sea levels were fluctuating(过去那段时间持续发生，用过去进行时). [引用客观规律,用现在时]When sea levels fall, the habitats for ocean populations that live in the shallows and land species that live on the coast are destroyed. The destruction of coastal and shallow-ocean species would have had(又回到过去，推测当时情况） a profound effect on food chains worldwide, leading to mass extinctions. （TPO39）
在中间展开的时候，用了 海平面下降会导致的结果--这一普遍的客观规律来论证，所以即使是讨论在the Triassic period时代的事情，中间也用了现在时。
3. Doubters point out that since modern reptiles are cold-blooded, ancient reptiles such as pterosaurs were probably cold-blooded as well. [引用客观现实]Cold-blooded animals typically have a slow metabolism and are unable to produce a lot of energy. Powered flight is an activity requiring a lot of energy, which is why all modern vertebrates that fly are warm-blooded, not cold-blooded. It seemed unlikely that pterosaurs would have been able to generate the energy needed to fly. （TPOP47）
总结划重点：
1. 表示阅读，听力观点，反驳的内容，都用一般现在时。
2. 综合写作内容主要是：现在政策，历史考古谜团。所以主要时态是，一般现在时，和一般过去时。
3. 特别需要注意的是，当阅读, 听力对现在/过去情况推测，做分析时，时态的正确使用。
PS: 大家在自己独立作文中，要对一个观点进行分析推理的时候，知道应该用什么时态了吗？
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