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Using the examples in the lecture, explain how the position of birds' eyes is critical to their survival.
請用課上所舉例子解釋說明為什么鳥類的眼睛對它們的生存至關(guān)重要。
Listen to part of a lecture in a biology class.
請聽生物課上的部分內(nèi)容。
Birds have some of the best vision capabilities in the animal kingdom.
在動物王國中，鳥類的視力是最好的之一。
Some birds species have vision that is eight to ten times greater than humans.
有些鳥類的視力比人類的要好八到十倍。
Overall, a bird's eyes are extremely important for its survival.
總的來說，一只鳥的眼睛對于它的存亡極其重要。
One aspect of bird's eyes that plays a role in helping them survive,
鳥的眼睛在幫助它們生存方面起作用的，
in other words to find food or to avoid predators, is the position of the eyes in the skull.
換句話說，能夠幫助它們找到食物或者躲避天敵的其中一部分，就是它們的眼睛在頭骨中的位置。
Some birds have eyes that face forward on the skull, kind of similar to how human's eyes are positioned.
有些鳥類的眼睛朝著頭骨前方生長，有點像人類眼睛的生長位置。
Forward-facing eyes allow a bird to clearly see and judge distances
眼睛朝前使得鳥類可以清楚地看見遠(yuǎn)方并判斷距離，
because it can focus on objects with both of its eyes, and correctly perceive height, width and depth.
因為它可以兩只眼睛一起關(guān)注物體，并且準(zhǔn)確地感知到高度、寬度和深度。
One type of bird with eyes positioned in the front of the skull is the hawk.
眼睛生長在頭骨前方的其中一種鳥類就是鷹。
Hawks eat animals like mice. Hawks have such good eye sight
鷹以老鼠這類小型動物為食。它們的視力非常好，
that they can spot a tiny mouse in the field from high up in the air.
可以從高空中捕捉到田野里一只小老鼠的蹤影。
They spot the mouse and swoop down to catch it.
它們看見老鼠后便會俯沖下來捉住它。
Without such good eye sight, they would not be able to spot or catch their food.
沒有這么好的視力的話，它們就不可能看見或者捉到獵物了。
Other birds have eyes that are located on each side of the skull.
也有其他鳥類的眼睛生長在頭骨兩側(cè)。
This positioning of the eyes can help a bird to avoid predators.
眼睛生長在這種位置可以幫助鳥類躲避捕食者。
Instead of just seeing what's directly in front,
除了只能看見正前方，
they can see things that are on either side, permitting them to watch for danger in all directions.
它們還看得見身體兩側(cè)的事物。這樣它們就能察覺到來自任何方位的危險了。
Imagine a duck wading near the edge of a lake.
想象一下一只鴨子正鳧在湖岸邊。
It needs to spend time eating grasses and insects,
它需要一些時間吃草和昆蟲，
but it also is on constant lookout for danger from its predator, like the fox.
但它同時也時刻警惕著，不斷察看有沒有捕食者的蹤影，比如狐貍。
An eye on each side of the duck's head allows it to see a fox approaching from either side.
鴨子頭上一邊一只的眼睛使得它能從任意一邊看見企圖接近它的狐貍。
If it spots a fox, it can then fly away to safety.
一旦發(fā)現(xiàn)了狐貍的蹤影，它就能立刻飛到安全的地方去。
The placement of the eyes are critical in helping the duck avoid predators.
眼睛的位置在幫助鴨子躲避捕食者時至關(guān)重要。
