自然学科是托福阅读文章题材中比较常见的类型，本系列为大家汇总整理了多篇托福阅读自然科学类文章，大家在托福备考时可以有针对性的进行复习，前程百利小编为大家带来的是托福阅读自然科学话题The Vision of Human，并附有相应的练习，希望大家都能顺利拿下托福阅读高分。
The Vision of Human
Keywords:eyes, red, Light, human, horse, ants, rattlesnake
Human vision, like that of other primates, has evolved in an arboreal environment. In the dense, complex world of a tropical forest, it is more important to see well than to develop an acute sense of smell. In the course of evolution, members of the primate line have acquired large eyes while the snout has shrunk to give the eye an unimpeded view. Of mammals, only humans and some primates enjoy color vision. The red flag is black to the bull. Horses live in a monochrome world.
Light visible to human eyes, however, occupies only a very narrow band in the whole electromagnetic spectrum. Ultraviolet rays are invisible to humans, though ants and honeybees are sensitive to them. Humans have no direct perception of infra-red rays, unlike the rattlesnake, which has receptors tuned in to wavelengths longer than 0.7 micron. The world would look eerily different if human eyes were sensitive to infra-red radiation.
Then, instead of the darkness of night, we would be able to move easily in a strange, shadowless world where objects glowed with varying degrees of intensity. But human eyes excel in other ways. They are, in fact, remarkably discerning in color gradation. The color sensitivity of normal human vision is rarely surpassed even by sophisticated technical devices.
1. What does the passage mainly discuss?
(A) Ultraviolet rays
(B) Human vision
(C) Sight and smell
(D) The environment of primates
2. Why does the author mention the "tropical forest" in line 2?
(A) To explain why primates have development keen vision
(B) To suggest that primates need to see only the color green
(C) To give an example of environmental change
(D) To indicate where large-eyed primates can be found
3. What does the author mean by stating that "The red flag is black to the bull" (lines 5-6)
(A) Bulls are attracted to red objects.
(B) Bulls to not notice flags.
(C) Bulls attack all flags.
(D) Bulls to not see the color red.
4. The word "monochrome" in line 6 is closest in meaning to which of the following?
(A) Monotonous
(B) Ultraviolet
(C) One-dimension
(D) One-color
5. In line 8, "them" refers to which of the following?
(A) Human eyes
(B) Ultraviolet rays
(C) Humans
(D) Wavelengths
6. According to the passage, which of the following can detect wavelengths of light longer than 0.7 micron?
(A) Bulls
(B) Horses
(C) Ants
(D) Rattlesnakes
7. The word "eerily" in line 10 is closest in meaning to which of the following?
(A) Strangely
(B) Increasingly
(C) Slightly
(D) Superficially
8. It can be inferred from the passage that humans could move more easily at night if they
(A) had a narrowed field of vision
(B) were color-blind
(C) had infrared vision
(D) lived in an arboreal environment
9. The word "surpassed" in line 15 is closest in meaning to which of the following?
(A) Recorded
(B) Exceeded
(C) Found
(D) Provided
10. According to the passage, the ability of human's to distinguish color differences is
(A) average
(B) weak
(C) excellent
(D) variable
11. Where in the passage does the author mention the development over time of certain physical changes among primates?
(A) Lines 3-4
(B) Lines 5-6
(C) Lines 7-10
(D) Lines 13-15
参考答案：BCDDB DACBC A
以上就是为大家整理的托福阅读自然科学类文章之The Vision of Human，希望能够帮助大家备考。预祝大家托福考试取得好成绩!
