About ten men in every hundred suffer from colour blindness in some way;women are luckier only about one in two hundred is affected in this manner．There are different forms of colour blindness．A man may not be able to see deep red．
He may think that red orange and yellow are all shades of green．Sometimes a person cannot tell the difference between blue and green．In rare cases an unlucky man may see everything in shades of green－a strange world indeed．
In certain occupations color blindness can be dangerous and candidates are tested most carefully．For example when fighting at night soldiers use lights of flares to signal to each other．A green light may mean“Advance”and a red light may mean“Danger!Keep back!”You can see what will happen if somebody thinks that red is green!Color blindness in human beings is a strange thing to explain．In a single eye there are millions of very small things called“cones”these help to see in a bright light and to tell the difference between colors．There are also millions of“rods”but these are used for seeing when it is nearly dark．They show us shape but not color．Wait until it is dark tonight then go outside．Look round you and try to see what colors you can recognize．
Birds and animals which hunt at night have eyes which contain few or no cones at all so they cannot see colors．As far as we know bats and adult owls cannot see colors at all only light and dark shapes．Similarly cats and dogs cannot see colors as well as we can．
Insects can see ultraviolet rays which are invisible to us and some of them can even see X-rays．The wings of a moth may seem grey and dull to us but to insects they may appear beautiful showing colors which we cannot see．Scientists know that there are other colors around us which insects can see but which we cannot see．Some insects have favorite colors．Mosquitoes like blue but do not like yellow．A red light will not attract insects but a blue lamp will．
(1)
Among people who suffer from color blindness ________．[]
A．some may see everything in shades of green
B．few can tell the difference between blue and green
C．few may think that red orange and yellow are all shades of green
D．very few may think that everything in the world is in green
(2)
When millions of rods in our eyes are at work in darkness we can see ________．[]
A．colors only
B．shapes and colors
C．shapes only
D．darkness only
(3)
According to the passage bats and adult owls cannot see colors ________．[]
A．because they hunt at night
B．because they cannot see light
C．because they have no cones and rods
D．because they have no cones
(4)
According to the passage dogs and cats ________．[]
A．as well as human beings can not see some colors
B．have fewer cones than human beings
C．have less rods than human beings
D．can see colors as well as human beings
(5)
Which of the following is NOT true about insects?[]
A．Insects can see more colors than human beings．
B．Insects can see ultraviolet rays which are invisible to men．
C．All insects have their favorite colors．
D．The world is more colorful to insects than to human beings．
答案：
1．D;2．C;3．D;4．B;5．C;
解析：
(1)在第二段最后一句中作者说在罕见的病例中，不幸的患者会把每一种色彩都当作是深浅不同的绿色。A、B、C的错误之处都在于对色盲人数多少的限定词some或few不够准确。
(2)这道细节题可以“rods”这个专业词帮助我们在第三段中间位置迅速定位，在这里，作者告诉我们视杆细胞(rod)在天色接近黑暗时发挥作用，他们能使我们看到物体的外形，而不是颜色。故选C项。
(3)这道题可从第四段第一、二句中找到，这两句告诉我们在夜晚捕食的鸟和动物的眼睛几乎没有或根本没有锥状细胞(cone)，所以不能区别颜色，而蝙蝠或猫头鹰就属于这样的动物。故D项正确。
(4)这是道推断题，第四段最后一句说，猫和狗识别颜色的能力不如人类，而前文又说了不能识别颜色是因为锥状细胞少，由此，我们可以推出猫和狗的锥状细胞不如人类多。这里易误选的是A项，注意文中的as well as用于否定句是“不如……好”的意思，是比较级的as…as形式，不是作为“也”意思讲的短语“as well as”。
(5)关于昆虫的讲述在文中的最后两段中，从这两段的叙述中，我们知道，昆虫能看到许多我们人类看不见的颜色，它们所看到紫外线和X射线，这里在讲到昆虫用的是表示类别的复数形式“insects”，代表的是所有的昆虫共有的特征，所以A、B、D的内容都是正确的，C的内容说所有的昆虫都有它们自己喜爱的颜色，而文中说的是一些昆虫有自己喜爱的颜色，所以C项的内容不对，为C项。