蜜蜂的眼睛是復眼，用于導航。它的眼睛有15000個面，把它看到的物體分割為馬賽克式的小點。[4]有了這種視覺特點，蜜蜂看到的太陽只是一個小點，一個不變的參照點。所以，它的眼睛是一個極好的導航儀器，能不斷地量度飛行的線路與太陽的角度。蜜蜂的眼睛還能測量飛行的速度。如果這樣還不能讓我們人類20/20的完美視力顯得微不足道的話，蜜蜂還能看到紫外線，這是我們人類無法看到的。因此，當我們與別的特種相比時,人類認為“完美的視力”實際上很有局限性的。然而，對于人類的眼睛還是有很多可以稱贊的：在所有哺乳動物當中，只有人類和某些靈長類動物能享受分辨顏色的喜悅。

　　1. The Snellen eye chart measures one'seyesight by__________________.

　　A) the number of lines he reads

　　B) the distance he stands away from the chart

　　C) the speed at which he recognizes the letters

　　D) several integrative factors

　　2. How is hawk's eyesight better than ours?

　　A) It can identify small items more quickly than we do.

　　B) It can see ai a longer distance than we do.

　　C) It has more cones in che retina than we do.

　　D) It has bigger eyes than we do.

　　3. Monocular vision enables the kingfisher to__________________.

　　A) avoid farsightedness

　　B) be able to see underwater

　　C) move one eye at a time

　　D) focus its eyes on the prey

　　4. A bee finds its direction by_______________________.

　　A) dividing what it sees into thousands of dots

　　B) constantly gauging its flying speed

　　C) using the sun as a constant point of reference

　　D) measuring the angle of the sun

　　5. What is the main idea of the passage'?

　　A) The differences between human eyes and other species' eyes.

　　B) The advantages of other species' eyes in comparison with human eyes.

　　C) The factors that make other species' eyes better than human eyes.

　　D) The standard that determines me "perfect vision” of human eyes.