Passage 1

　　We know that many animals do not stay in one place. Birds, fish and other animals move from one place to another at a certain time. They move for different reasons: most of them move to find food more easily, but others move to get away from places that are too crowded.

　　When cold weather comes, many birds move to warmer places to find food. Some fishes give birth in warm water and move to cold water to feed. The most famous migration (迁移) is probably the migration of fish, which is called “salmon”. This fish is born in fresh water but it travels many miles to salt water. There it spends its life. When it is old, it returns to its birthplace in fresh water. Then it gives birth and dies. In northern Europe, there is a kind of mouse. They leave their mountain homes when they become too crowded. They move down to the low land. Sometimes they move all the way to the seaside, and many of them are killed when they fall into the sea.

　　Recently (近来), scientists have studied the migration of a kind of lobster (龙虾). Every year,

　　when the season of the bad weather arrives, the lobsters get into a long line and start to walk

　　across the floor of the ocean. Nobody knows why they do this, and nobody knows where they go.

　　So, sometimes we know why humans and animals move from one place to another, but at other

　　times we don’t. Maybe living things just like to travel.

　　1.Most animals move from one place to another at a certain time to _______.

　　A.give birth B. enjoy warmer weather

　　C. find food more easily D. find beautiful places

　　2.The fish called “salmon” spends a long time in ______.

　　A. salt water B. rivers C. fresh water D. its birthplace

　　3.The mice in northern Europe move when _______.

　　A. they give birth B. the place gets too crowded

　　C. the weather is bad D. they haven’t enough food

　　4.The lobsters move ________.

　　A. to the fresh water B. at a certain time C. to the undersea D. to find more food

　　5.What is the main idea of the passage?

　　A.Animals move to find food more easily.

　　B.The migration of the fish called “salmon” is the most famous migration.

　　C.Living things move from one place to another because they like to travel.

　　D. Sometimes we know why and how living things move from one place to another, but sometimes we don’t.

　　Passage 2

　　If you look at the sky one night and see something moving and shining that you have never seen before, it might be a comet (彗星).

　　A comet sometimes looks like a star. Like a planet, a comet has no light of its own. It shines from the sunlight it reflects (反射). Like the earth, a comet goes round the sun, but on a much longer path (轨道) than the earth travels.

　　If a comet isn’t a star, what is it then?

　　Some scientists think that a large part of a comet is water frozen into pieces of ice and mixed with iron and rock dust and perhaps a few big pieces of rock. When sunshine melts (融化) the ice in the comet, great clouds of gas go trailing after it. These clouds, together with the dust, form a long tail.

　　Many people perhaps have seen a comet. However no one knows how many comets there are. There may be millions of comets, but only a few come close enough for us to see.

　　An Englishman named Edmund Halley, who lived from 1656 to 1742, found out a lot about the paths that comets take through the sky. Some comets move out of our sight and never come back. Others keep coming back at regular times. A big comet that keeps coming back was named after Halley because he was the one who worked out when it would come back again. Maybe you have ever seen Halley’s Comets because the last time it came close to the sun and the earth was in the year 1986. Then people all over the world were outside at night to look at it. You will probably be able to see Halley’s Comets when it comes near the earth again.

　　1.A comet is like ________.

　　A. sun B. moon C. sunlight D. the earth

　　2.A large part of a comet is ______.

　　A.water and rock B. water frozen into pieces of ice and mixed with iron

　　C. ice, iron and rock dust D. only a few big pieces of rock

　　3.Maybe many people _______.

　　A. haven’t seen any comets B. have seen all comets

　　C. have seen a comet at daytime D. have seen a comet

　　4.Some comets keep coming back ________.

　　A. at any time B. at noon C. at regular times D. at daytime

　　5.Halley’s Comets came back _____.

　　A. in 1990 B. in 1980 C. in 1986 D. in 1989