托福听力讲座中开头和结尾部分往往是许多题目的出题点所在，因此大家如果能够在听的过程中把握好这两个部分，今天小编给大家带来了托福听力讲座开头结尾常见信号词汇总一览，希望能够帮助到大家，下面小编就和大家分享，来欣赏一下吧。
托福听力讲座开头结尾常见信号词汇总一览
托福听力讲座开头部分信号词一览
说话者表达主旨或谈话的目的的语句往往出现在开头的几句话，是把握全局的重点。
信号词：(专家建议考生，每天要把所有的信号词读个几遍，强迫自己听到这个词马上反应过来这里有考点)
Today, we’ll focus on/constrated/discuss…
Today, our topic is…
Let’s…
特殊情况(也经常出现)：开头会将讲一些上次课讲的东西，作为复习，之后才是主旨，我们把这种情况称为：Miss start
注意：出现Miss Start，上次课讲的东西一定要听，在这部分很可能出细节题
Miss Start 信号词：Before we get started, let’s review what we’ve learned last class…
Let’s pick up where we left off last week, OK, as you recall(记得)…
Before we begin our discussion on…(此处为本次主题)，Let’s review what we know about…(此处为上次主题)
间接开头： In your text book, the author says that… (主题出现)，I thought we all to/should take sometime to talk about it. (不一定完全一样，但是类型差不多)
托福听力讲座结尾部分信号词汇总
托福听力的结尾部分往往出现一些总结性信息以及其他一些涉及考点的内容，应充分重视。
信号词：
To some up
To conclude/in conclusion
In summary/to summarize
Finally
Therefore
From this, we can see that…
2020托福听力练习：蜜蜂通过味道给花粉排名
Walk through Times Square—you're bombarded with advertising. And it turns out, a bumblebee might have a similar feeling, buzzing through a field of flowers. "So these flowers are these billboards, they're advertising a good, this delicious nectar reward, and bees are very picky shoppers." Anne Leonard, a pollination biologist at the University of Nevada, Reno.
She describes a flower field as a sort of pollination marketplace. And one way bees choose where to visit? "Bees are nectar experts. They are really good at assessing even really small differences in the sugar concentration of nectar." They also scope out the shape and size of the flowers, and their color and scent. And now Leonard and her colleagues have discovered that bumblebees are pollen aficionados, too.
They found that out by lacing batches of cherry pollen with either table sugar or bitter quinine. And to display the pollen to bees, "We got really into it—we started 3-D printing flowers in our lab." And for the anther—the male flower part, which presents the pollen—pipe cleaners. "So we bought out Michael's craft store supplies of these pipe cleaners and used them in our experiments."
Turns out bees would return again and again to the same color flower that dispensed sweet pollen, and spend more time collecting there. But when confronted with the bitter pollen? They sought a different colored flower for their very next stop. All of which suggests that, in addition to savoring nectar, bees taste pollen too—and judge flowers by it. The results are in the journal Biology Letters.
The finding means that plants have to find a happy medium: "So can you make your pollen attractive enough that the bees will collect it, but distasteful enough that they won't collect too much of it?" And that balancing act, of carefully calibrated chemistry—it's just one of the many transactions that plays out in the buzzing pollination marketplace. Where the object is to make a sweet profit.
走过纽约时代广场，你会被广告不断侵扰。事实证明，熊蜂在嗡嗡地飞过花田时，可能会有类似的感觉。“因为这些花朵就像是那些广告牌，它们在为这些美味可口的花蜜打广告，而蜜蜂就是那些非常挑剔的消费者。”内华达州立大学雷诺分校的传粉生物学家安妮·伦纳德说道。
她将花田描述为一个授粉市场。蜜蜂选择去哪里采集花蜜的方法是什么?“蜜蜂是花蜜专家。它们很擅长评估花蜜，即使花蜜糖的浓度存在微小的区别它们也能感觉到。”它们还能确定花的形状、大小、颜色和气味。现在伦纳德和她的研究团队发现，熊蜂也是花粉爱好者。
他们通过给不同批次分别含有甜蔗糖和苦奎宁的樱桃花粉系上标签的方法进行研究，并得到了上述结论。为了向蜜蜂展示花粉，“我们进行了非常深入地研究，我们开始在实验室用3D技术打印花朵。”在花药部分，也就是呈现出花粉的雄花部分使用清管器。“所以我们购买了迈克尔工艺品店的清管器，将这些清管器应用到我们的实验中。”
实验证明，蜜蜂会在含有甜蔗糖花粉的相同颜色花朵间重复往返，并且花费更多的时间来采集。那它们遇到含有苦奎宁的花粉时会怎样呢?它们会在下一次停留时寻找一种与之颜色不同的花朵。所有这一切表明，除了品尝花蜜，蜜蜂也会品尝花粉的味道，并且通过花粉来对花朵进行评估。该研究结果刊登在《生物学快报》杂志上。
该研究结果表明，植物必须找到一个折中的办法：“你能让你的花粉有足够的吸引力，让蜜蜂来采集，但是又让花粉不太合口，确保蜜蜂不会采集太多吗?”这一精确校准化学的平衡做法，只是蜜蜂授粉市场上进行的众多交易中的其中一种。该市场的目标是获得“甜蜜”的利润。
重点讲解：
1. be good at 擅长的;精通的;能干的;
例句：The conductor is good at keeping the players together.
乐队指挥善于使表演者奏协调。
2. buy out 买下…的股权(或产权);
例句：The bank had to pay to buy out most of the 200 former partners.
银行不得不花钱买下过去200名合伙人手中的大部分股权。
3. be confronted with (问题、任务或困难)降临，使面临;
例句：There is always turmoil when humans are confronted with change.
当人类面对改变的时候，总是有混乱。
4. in addition to 另外;加之;除…之外;
例句：In addition to the radio, newspapers were also a main source for information.
除了无线电广播外，报纸也是一种主要信息来源。
5. play out (使)(戏剧性的事件)逐渐发生;(使)展开;
例句：We play out an imaginary confrontation in our mind.
我们的脑海中浮现出一种想象的冲突。
2020托福听力练习：海豚通过鼻涕粘液发声
Sometimes a snout full of snot can be just what the doctor ordered. At least if you're a dolphin. Because a new study shows that a little bit of mucus helps these marine mammals generate the rapid-fire stream of clicks they emit and use for echolocation.
First off, let's just get this out of the way. Dolphins do not actually sound like this. [Flipper laugh sound] That's a made-for-TV giggle that some say is actually the doctored call of a bird: the Australian kookaburra.
Real dolphins, like these bottlenoses, sound more like this. [Bottlenose sounds] They use their clicks, chirps and whistles to navigate, communicate and to catch their next meal. The high-frequency clicks, in particular, help Flipper and his kind locate and track fish dinners.
Dolphins make these sounds by forcing air through a nasal passage just beneath the blowhole. In this nasal region are liplike flaps of tissue called dorsal bursae that vibrate and collide to produce dolphin talk.
Now, a team of researchers has created a simplified model that can reproduce this characteristic dolphin chatter. And they found that the secret ingredient is snot.
While looking through the literature, oceanographer Aaron Thode stumbled across a model that represented vocal cords as masses connected by springs—which store and release energy—and dampers, which dissipate that energy. This model successfully replicated the essential characteristics of the system, like the frequency of vocal cord vibration.
So Thode enlisted his father Lester, a retired nuclear physicist from Los Alamos National Lab, to help him fit the model to a dolphin's nasal anatomy. When the Thodes compared the simulated sounds produced by their model to a recording of actual dolphins, they found that the model mimicked both the loud thump and extended ring that are part of the natural click. That's the sound, but slowed down to make it audible to our ears.
The initial thud comes from when those dorsal bursae collide. And the reverberation results from the vibrations that linger when the tissues pull apart. But Thode the younger says the bursae have to be somewhat sticky for the clapping together and snapping apart to produce a noise with the correct loudness and pitch. That stickiness comes courtesy of the mucus. Thode vocalized the results at the meeting of the Acoustical Society in Salt Lake City.
The match between the simulated sounds and the real deal is encouraging, and the Thodes plan to keep up their collaboration to refine their model. "Yeah, I guess some fathers and sons bond over football, but my dad and I, I guess we bonded over differential equations and writing this paper."
如果你是一只海豚，医生会要求你鼻子里充满鼻涕。因为一项新研究表明，一点粘液有助于这些海洋哺乳动物发出急速连续的咔哒声并利用回声进行定位。
首先，我们要说明一下。海豚实际上并不会发出这样的声音。(海豚飞宝的笑声)这种咯咯的笑声出自一部电视电影，有人说那实际上是用澳大利亚笑翠鸟的叫声伪造的。
真正的海豚，像这些宽吻海豚，它们的声音听起来更像这样。(宽吻海豚的声音)它们通过发出的咔哒声、啾啾声和口哨声来进行导航、交流和捕食。尤其高频咔哒声可以帮助海豚飞宝和它的同类进行定位，追踪用作晚餐的鱼类。
海豚迫使空气穿过气孔之下的鼻道制造出声音。海豚的鼻区有被称为背侧黏液囊的唇形片状瓣膜，通过振动和碰撞让海豚能够“讲话”。
现在，一个研究小组建立了一个可重现海豚叫声特征的简化模型。他们发现，秘密成分是鼻涕。
在浏览文献时，海洋学家亚伦·索德偶然发现了一个模型，这个模型将声带描绘成由弹簧相连、可以储藏和释放能量的集块，以及消散能量的阻尼器。这一模型成功地复制了发声系统的基本特征，如声带振动的频率。
索德的父亲是美国洛斯阿拉莫斯国家实验室的退休核物理学家，索德邀请他的父亲莱斯特加入研究，帮助他使这个模型与海豚的鼻部解剖构造相符合。当他们将模型产生的模拟声音与海豚真实声音的录音进行比较时，他们发现，这个模型模拟的撞击声和延长形成的环状结构就是海豚发出的咔哒声的一部分。这就是模型发出的声音，不过我们放慢了速度让大家可以听清。
最初的撞击声来自背侧黏液囊的碰撞。而回声则来源于组织分离时产生的振动。不过小索德认为，黏液囊必须要有足够的粘性，一下靠拢又分开，才能产生这种声音并达到正确的音量和音高。这种粘性来自粘液。索德在盐湖城举行的声学学会上发表了这一研究成果。
模拟声音与海豚原声的匹配度令人鼓舞，索德父子计划继续合作下去，完善他们的模型。“我认为有些父子因足球而亲密，而我爸爸和我是因为微分方程和撰写这篇论文而亲密起来的。”
重点讲解：
1. in particular 尤其;特别;
例句：She stressed that point in particular.
她特别强调了那一点。
2. stumble across 意外发现;偶然看见;
例句：I stumbled across an extremely simple but very exact method for understanding where my money went.
我意外发现了一个非常简单却能精确了解我所花钱去向的方法。
3. part of 一些;部分;
例句：The astronaut accepted danger was part of the job.
太空人承认他们的工作中包含著危险。
4. keep up 继续做(或提供);
例句：You can't keep up the pretense any longer.
你无法继续伪装下去了。
