competitiveness2020年12月英语六级模拟题：阅读

2021年1月8日发(作者：程相文)
2020年12月英语六级模拟题：阅读

2020年12月英语六级模拟题：阅读

小编推荐：

You stare at waterfall for a minute or two, and then
shift your gaze to its surroundings. What you now see appears
to drift upward.

These optical illusions occur because the brain is
constantly matching its model of reality to signals from the
body’s sensors and interpreting what must be happening—that
your brain must have moved, not the other; that downward
motions is now normal, so a change from it must now be
perceived as upward motion.

The sensors that make this magic are of two kinds. Each
eye contains about 120 million rods, which provide somewhat
blurry black and white vision. These are the windows of night
vision; once adapted to the dark, they can detect a candle
burning ten miles away.

Color vision in each eye comes from six to seven million
structures called cones. Under ideal conditions, every cone
can “see” the entire rainbow spectrum of visible colors,
but one type of cone is most sensitive to red, another to
green, a third to blue.

Rods and cones send their messages pulsing an average 20
to 25 times per second along the optic nerve. We see an image
for a fraction of a second longer than it actually appears.
In movies, reels of still photographs are projected onto