2015年9月公共英語三級考試考前強(qiáng)化練習(xí)題（4）

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　　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 colour 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! Colour 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 colours. There are also millions of “rods” but these are used for seeing when it is nearly dark. They show us shape but not colour. 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 colours. As far as we know, bats and adult owls cannot see colours at all only light and dark shapes. Similarly cats and dogs cannot see colours as well as we can.

　　Insects can see ultraviolet 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 colours which we cannot see. Scientists know that there are other colours around us which insects can see but which we cannot see. Some insects have favorite colours. Mosquitoes like blue, but do not like yellow. A red light will not attract insects but a blue lamp will.

　　51. Among people who suffer from colour blindness, .

　　[A] some may see everything in shades of green

　　[B] few can tell the difference between blue and green

　　[C] very few may think that everything in the world is in green

　　[D] few may think that red, orange and yellow are all shades of green

　　52. When millions of rods in our eyes are at work in darkness we can see.

　　[A] colours only

　　[B] shapes and colours

　　[C] shapes only

　　[D] darkness only

　　53. According to the passage, bats and adult owls cannot see colours.

　　[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

　　54. According to the passage, dogs and cats.

　　[A] as well as human beings can not see some colours

　　[B] have fewer cones than human beings

　　[C] have less rods than human beings

　　[D] can see colours as well as human beings

　　55. Which of the following is not true about insects?

　　[A] Insects can see more colours than human beings.

　　[B] Insects can see ultraviolet rays which are invisible to men.

　　[C] All insects have their favorite colours.

　　[D] The world is more colorful to insects than to human beings.

　　答案：

　　51. [C]在第一段最后一句中作者說在罕見的病例中，不幸的患者會把每一種色彩都當(dāng)作是深淺不同的綠色。A、B、D的錯誤之處都在于對色盲人數(shù)多少的限定詞some或few不夠準(zhǔn)確。

　　52. [C]這道細(xì)節(jié)題可以“rods”這個專業(yè)詞匯幫助我們在第三段中間位置迅速定位，在這里，作者告訴我們視桿細(xì)胞(rod)在天色接近黑暗時發(fā)揮作用，他們能使我們看到物體的外形，而不是顏色。故選C。

　　53. [D]這道題可從第四段第一二句中找到答案，這兩句告訴我們在夜晚捕食的鳥和動物的眼睛幾乎沒有或根本沒有錐狀細(xì)胞(cone)，所以不能區(qū)別顏色。而蝙蝠或貓頭鷹就屬于這樣的動物。故D正確。

　　54. [B]這是道推斷題，文章第四段最后一句說，貓和狗識別顏色的能力不如人類，而前文又說了不能識別顏色是因為椎狀細(xì)胞少，由此，我們可以推出貓和狗的椎狀細(xì)胞不如人類多。這里易誤選的是A答案，注意文中的as well as是不如……好的意思，是比較級的as... as形式，不是作為“也”意思講的短語“as well as”。

　　55. [C]關(guān)于昆蟲的講述在文中的最后兩段中，從這兩段的敘述中，我們知道，昆蟲能看到許多我們?nèi)祟惪床灰姷念伾?，它們所看到紫外線和X射線，這里在講到昆蟲用的是表示類別的復(fù)數(shù)形式“insects”，代表的是所有的昆蟲共有的特征，所以A、B、D的內(nèi)容都是正確的，C的內(nèi)容說所有的昆蟲都有它們自己喜愛的顏色，而文中說的是一些昆蟲有自己喜愛的顏色，所以C的內(nèi)容不對，答案為C。