【托福真题_英语外教一对一培训】栏目更新了TOEFL托福阅读真题及答案（64），以下为具体内容：

　　TOEFL托福阅读真题文章：

　　The Evolution of Birds

　　The evolution of birds is a fascinating area of study that has been greatly illuminated by recent fossil discoveries. Birds are now widely accepted to be descendants of theropod dinosaurs, a group that includes well-known predators such as Tyrannosaurus rex and Velociraptor. The transition from dinosaurs to birds involved a series of adaptations that allowed some theropods to become increasingly specialized for an arboreal or aerial lifestyle.

　　One of the key adaptations in bird evolution was the development of feathers. Feathers likely evolved initially for insulation or display purposes rather than flight. Early feathers were simple, hair-like structures, but over time they became more complex, with barbs and barbules that could interlock to form a flat surface. This structure is essential for flight feathers, which generate lift and thrust.

　　Another important adaptation was the reduction of body size. Smaller body size would have reduced the metabolic requirements for flight and allowed for more agile movement. Many early bird-like theropods, such as Archaeopteryx, were relatively small compared to their larger dinosaur relatives. Additionally, the development of a lightweight skeleton, with hollow bones and a fused sternum (breastbone), provided structural support for flight muscles while minimizing weight.

　　The evolution of flight itself is a subject of debate. Two main hypotheses have been proposed: the "trees down" hypothesis and the "ground up" hypothesis. The trees down hypothesis suggests that flight evolved from gliding behaviors in arboreal dinosaurs, which used feathers to control their descent from trees. The ground up hypothesis, on the other hand, posits that flight evolved from running and leaping behaviors in cursorial (ground-dwelling) dinosaurs, with feathers initially used for balance or to enhance running speed.

　　TOEFL托福阅读真题题目：

　　1. According to the passage, birds are descendants of which group of dinosaurs?

　　A. Sauropods

　　B. Theropods

　　C. Stegosaurs

　　D. Ankylosaurs

　　2. What was the likely initial function of feathers?

　　A. Flight

　　B. Insulation or display

　　C. Camouflage

　　D. Protection from predators

　　3. Why was the reduction of body size important in bird evolution?

　　A. It allowed dinosaurs to hunt more effectively

　　B. It reduced the metabolic requirements for flight

　　C. It made dinosaurs more visible to predators

　　D. It increased the strength of flight muscles

　　4. The word "arboreal" in the passage is closest in meaning to:

　　A. Ground-dwelling

　　B. Tree-dwelling

　　C. Aquatic

　　D. Nocturnal

　　5. According to the passage, what is one function of the fused sternum in birds?

　　A. It protects the heart and lungs

　　B. It provides structural support for flight muscles

　　C. It helps with digestion

　　D. It allows for better balance during flight

　　6. What is the main difference between the "trees down" and "ground up" hypotheses?

　　A. The trees down hypothesis focuses on the role of feathers, while the ground up hypothesis does not

　　B. The trees down hypothesis suggests flight evolved from gliding in trees, while the ground up hypothesis suggests it evolved from running on the ground

　　C. The trees down hypothesis is supported by fossil evidence, while the ground up hypothesis is not

　　D. The trees down hypothesis applies to all birds, while the ground up hypothesis applies only to certain species

　　7. The word "cursorial" in the passage is closest in meaning to:

　　A. Tree-dwelling

　　B. Fast-running

　　C. Aquatic

　　D. Flightless

　　8. According to the passage, what is an important feature of flight feathers?

　　A. They are solid and heavy

　　B. They have barbs and barbules that interlock

　　C. They are only found on the wings

　　D. They evolved before non-flight feathers

　　9. Which of the following can be inferred from the passage about Archaeopteryx?

　　A. It was a fully developed modern bird

　　B. It was larger than most theropod dinosaurs

　　C. It had features of both dinosaurs and birds

　　D. It could fly as well as modern birds

　　10. The author mentions Tyrannosaurus rex and Velociraptor in order to:

　　A. Contrast their size with that of early birds

　　B. Provide examples of non-avian theropod dinosaurs

　　C. Explain why some dinosaurs became extinct

　　D. Illustrate the diversity of dinosaur species

　　TOEFL托福阅读真题答案参考：

　　B、B、B、B、B、B、B、B、C、B

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