(1-1A) The fiddler crab(Af )is a living clock. It tells the time of day by the color of its skin. which is dark by day and pale by night. The crab's changing skin color follows a regular twenty-four hour cycle that exactly matches the daily rhythm of the sun Does the crab actually keep time, or does its skin simply respond to the suns rays, changing color according to the amount of light that strikes it? To find out, biologists kept crabs in a dark room for two months. Even without daylight the crab's skin color continued to change exactly on schedule Perhaps this feature developed gradually in response to the rhythm of the sun, to help protect the crab from sunlight and enemies. After millions of years it had become completely fixed inside the g body of the crab The biologists noticed that once each day the color of the fiddler crab is especially dark, and that each day this occurs fifty minutes later than on the day before. From this they discovered that each crab follows not only the rhythm of the sun but also that of the tides. The crab's period of greatest darkening is the time of low tide on the beach where it was caught 1. The crab's changing skin color follows A)the daily rhythm of the sun B) the rhythm of the tides C)the suns D)both A and B 2. The experiment carried out by the biologists shows that A)only in a dark room it changes color B)its changing skin color follows a regular cycle C)it changes color every fifty minutes 3. What's the function of crab's color-changing ability? .ight D) Its color-changing ability has nothing to do with A)Keep warm B)Protect himself from enemies and sunlight C)Keep time D)Respond to the suns rays 4. The sentence"The crab's skin color continued to change exactly on schedule. in the second paragraph means that A)It still changed in a regular twenty-four hour cycle B)it changed color more slowly C) it didnt change color at all D)it changed color more quick 5. The passage is probably taken from a book of A)science B) geography C)biology D) physiology 3.B 4.A 1-1B) The fiddler crab(Bt)is a living clock. It tells the time of day by the color of its skin. Which is dark by day and pale by night. The crab's changing skin color follows a regular twenty-four hour cycle that exactly matches the daily rhythm of the sun Does the crab actually keep time, or does its skin simply respond to the suns rays, changing color according to the amount of light that strikes it? To find out, biologists kept crabs in a dark room for two months. Even without daylight the crab's skin color continued to change exactly on schedule Perhaps this feature developed gradually in response to the rhythm of the sun, to help protect the crab from sunlight and enemies. After millions of years it had become completely fixed inside the living body of the crab The biologists noticed that once each day the color of the fiddler crab is especially dark, and that each day this occurs fifty minutes later than on the day before. From this they discovered that each( 1 – 1 A ) The fiddler crab (蟹) is a living clock. It tells the time of day by the color of its skin. Which is dark by day and pale by night. The crab’s changing skin color follows a regular twenty-four hour cycle that exactly matches the daily rhythm of the sun. Does the crab actually keep time, or does its skin simply respond to the sun’s rays, changing color according to the amount of light that strikes it? To find out, biologists kept crabs in a dark room for two months. Even without daylight the crab’s skin color continued to change exactly on schedule. Perhaps this feature developed gradually in response to the rhythm of the sun, to help protect the crab from sunlight and enemies. After millions of years it had become completely fixed inside the living body of the crab. The biologists noticed that once each day the color of the fiddler crab is especially dark, and that each day this occurs fifty minutes later than on the day before. From this they discovered that each crab follows not only the rhythm of the sun but also that of the tides. The crab’s period of greatest darkening is the time of low tide on the beach where it was caught! 1.The crab’s changing skin color follows __________. A) the daily rhythm of the sun B) the rhythm of the tides C) the sun’s rays D) both A and B 2.The experiment carried out by the biologists shows that __________. A) only in a dark room it changes color B) its changing skin color follows a regular cycle C) it changes color every fifty minutes D) Its color-changing ability has nothing to do with daylight 3.What’s the function of crab’s color-changing ability? A) Keep warm. B) Protect himself from enemies and sunlight. C) Keep time. D) Respond to the sun’s rays. 4.The sentence “The crab’s skin color continued to change exactly on schedule.” in the second paragraph means that __________ A) It still changed in a regular twenty-four hour cycle B) it changed color more slowly C) it didn’t change color at all D) it changed color more quickly 5.The passage is probably taken from a book of __________. A) science B) geography C) biology D) physiology 1.D 2.B 3.B 4.A 5.C (72.66%) ( 1 – 1 B ) The fiddler crab (蟹) is a living clock. It tells the time of day by the color of its skin. Which is dark by day and pale by night. The crab’s changing skin color follows a regular twenty-four hour cycle that exactly matches the daily rhythm of the sun. Does the crab actually keep time, or does its skin simply respond to the sun’s rays, changing color according to the amount of light that strikes it? To find out, biologists kept crabs in a dark room for two months. Even without daylight the crab’s skin color continued to change exactly on schedule. Perhaps this feature developed gradually in response to the rhythm of the sun, to help protect the crab from sunlight and enemies. After millions of years it had become completely fixed inside the living body of the crab. The biologists noticed that once each day the color of the fiddler crab is especially dark, and that each day this occurs fifty minutes later than on the day before. From this they discovered that each