廣泛的托福閱讀背景知識積累，有助于新托福閱讀速度和準確率的提升。托福閱讀題材分為自然科學、人文科學、互聯網等幾大類，如果同學們平時能對這些種類的文章都有所涉獵，托福閱讀考試中遇到相關的話題就會有非常熟悉的感覺。在2014年5月25日的托福閱讀考試中有這樣一道題：雨林中動物傳遞信息的方式。針對這道托福考試，幫大家普及一下關于雨林中動物傳遞信息的方式背景知識，這樣有助于大家在面對這類題目時方便作答。
　　托福閱讀真題再現：
　　講的是動物、昆蟲的發聲的問題。
　　最開始怎么說的記不清楚了，第一層應該就是rain forest里面的小東東怎么讓聲音傳播。熱帶雨林里面這么吵，要讓同類聽到自己還是很不容易的，尤其對于那些小昆蟲什么的，而且很多小東西通過發聲來求偶交配嘛，你們都懂的!!!Rain forest這里舉了一個樹蛙的例子，就是這小青蛙用的一種招數，它一般會進到有水的樹洞， 身體一部分沒入水中，然后開始發聲，找到與大樹能共鳴的頻率，這不就能傳的更高更遠嘛。(有排除題)
　　下面一層應該是講birds，同時提到了它們叫的時間一般是在早上和黃昏，那個時候聲音能傳得更遠， 但是有些時候也會讓天敵們發現之類的(沒記錯的話，最少有倆道題)
　　最后一層應該是提到了不同物種的發聲頻率不同，這能讓它們被分辨出來。還有一個教授，把聲音錄下來回去分析，發現每個雨林的聲音還不太一樣，也是unique的，甚至可以像人類的指紋一樣去分辨樹林的獨特聲音什么的(有題)。
　　相關背景知識：
　　The daytime quality of light in forests varies with the density of the vegetation, the angle of the Sun, and the amount of cloud in the sky. Both animals and plants have different appearances in these various lighting conditions. A color or pattern that is relatively indistinct in one kind of light may be quite conspicuous in another.
　　In the varied and constantly changing light environment of the forest, an animal must be able to send visual signals to members of its own species and at the same time avoid being detected by predators. An animal can hide from predators by choosing the light environment in which its pattern is least visible. This may require moving to different parts of the forest at different times of the day or under different weather conditions, or it may be achieved by changing color according to the changing light conditions. Many species of amphibians (frogs and toads) and reptiles (lizards and snakes) are able to change their color patterns to camouflage themselves. Some also signal by changing color. The chameleon lizard has the most striking ability to do this. Some chameleon species can change from a rather dull appearance to a full riot of carnival colors in seconds. By this means, they signal their level of aggression or readiness to mate.
　　Other species take into account the changing conditions of light by performing their visual displays only when the light is favorable. A male bird of paradise may put himself in the limelight by displaying his spectacular plumage in the best stage setting to attract a female. Certain butterflies move into spots of sunlight that have penetrated to the forest floor and display by opening and closing their beautifully patterned wings in the bright spotlights. They also compete with each other for the best spot of sunlight.
　　Very little light filters through the canopy of leaves and branches in a rain forest to reach ground level—or close to the ground—and at those levels the yellow-to-green wavelength predominate. A signal might be most easily seen if it is maximally bright. In the green-to-yellow lighting conditions of the lowest levels of the forest, yellow and green would be the brightest colors, but when an animal is signaling, these colors would not be very visible if the animal was sitting in an area with a yellowish or greenish background. The best signal depends not only on its brightness but also on how well it contrasts with the background against which it must be seen. In this part of the rain forest, therefore, red and orange are the best colors for signaling, and they are the colors used in signals by the ground-walking Australian brush turkey. This species, which lives in the rain forests and scrublands of the east coast of Australia, has a brown-to-black plumage with bare, bright-red skin on the head and a neck collar of orange-yellow loosely hanging skin. During courtship and aggressive displays, the turkey enlarges its colored neck collar by inflating sacs in the neck region and then flings about a pendulous part of the colored signaling apparatus as it utters calls designed to attract or repel. This impressive display is clearly visible in the light spectrum illuminating the forest floor.
　　Less colorful birds and animals that inhabit the rain forest tend to rely on forms of signaling other than the visual, particularly over long distances. The piercing cries of the rhinoceros hornbill characterize the Southeast Asian rain forest, as do the unmistakable calls of the gibbons. In densely wooded environments, sound is the best means of communication over distance because in comparison with light, it travels with little impediment from trees and other vegetation. In forests, visual signals can be seen only at short distances, where they are not obstructed by trees. The male riflebird exploits both of these modes of signaling simultaneously in his courtship display. The sounds made as each wing is opened carry extremely well over distance and advertise his presence widely. The ritualized visual display communicates in close quarters when a female has approached.