_______ a pair of compasses, it is easy to describe a circle.

A. Having      B. To have had

C. If you have D. if having

練習(xí)冊系列答案
相關(guān)習(xí)題

科目：高中英語 來源：2010年上海市虹口區(qū)高三下學(xué)期質(zhì)量監(jiān)控考試（英語） 題型：閱讀理解

Birds that are half-asleep—with one brain hemisphere (半球) alert and the other sleeping—control which side of the brain remains awake, according to a new study of sleeping ducks.
Earlier studies have documented half-brain sleep in a wide range of birds. The brain hemispheres take turns sinking into the sleep stage characterized by slow brain waves. The eye controlled by the sleeping hemisphere keeps shut, while the wakeful hemisphere’s eye stays open and alert. Birds also can sleep with both hemispheres resting at once.
Decades of studies of bird groups led researchers to predict extra alertness in the end-of-the-row sleepers which tend to be attacked more easily. Sure enough, the end birds tended to watch carefully on the side away from their companions. Ducks in the inner spots showed no preference for gaze direction.
Also, birds napping at the end of the line depend on single-hemisphere sleep, rather than total relaxation, more often than inner ducks did. Turning 16 birds through the positions in a four-duck row, the researchers found that compared with 12 percent for birds in internal spots, outer birds half-asleep during some 32 percent of napping time.
“We believe this is the first evidence for an animal behaviorally controlling sleep and wakefulness at the same time in different regions of the brain,” the researchers say.
The results provide the best evidence for a long-standing assumption that single-hemisphere sleep evolved as creatures scanned for enemies. The preference for opening an eye on the lookout side could be widespread, he predicts. He’s seen it in a pair of birds napping side-by-side in the zoo and in a single pet bird sleeping by a mirror. The mirror-side eye closed as if the reflection were a companion and the other eye stayed open.
Useful as half-sleeping might be, it’s only been found in birds and such water animals as dolphins, whales, and seals. Perhaps keeping one side of the brain awake allows a sleeping animal to surface occasionally to avoid drowning.
Studies of birds may offer unique insights into sleep. Jerome M. Siegel of the UCLA says he wonders if birds’ half-brain sleep “is just the tip of the iceberg.” He supposes that more examples may turn up when we take a closer look at other species.
72. According to the passage, birds often half sleep because ______.
A. they have to watch out for possible attacks
B. their brain hemispheres take turns to rest
C. the two halves of their brain are differently structured
D. they have to constantly keep an eye on their companions
73. What is implied about the example of a bird’s sleeping in front of a mirror?
A. An imagined companion gives the bird a sense of security.
B. Birds prefer to sleep in pairs for the sake of their security.
C. The phenomenon of birds napping in pairs is widespread.
D. A single pet bird enjoys seeing its own reflection in the mirror.
74. While sleeping, some water animals tend to keep half awake in order to ______.
A. alert themselves to the approaching enemy
B. emerge from water now and then to breathe
C. be sensitive to the ever-changing environment
D. avoid being swept away by rapid currents
75. By saying “just the tip of the iceberg”, Siegel suggests that ______.
A. half-brain sleep has something to do with icy weather
B. the mystery of half-brain sleep is close to being solved
C. most birds living in cold regions tend to be half sleepers
D. half-brain sleep may exist among other species

查看答案和解析>>

科目：高中英語 來源：2016屆河北省高一上學(xué)期期中考試英語試卷（解析版） 題型：閱讀理解

Trip 1  Black Bear Count

  There have been fires in this area in the last few years and the Office of the National Park is not sure how many black bears are still living. Some bears have been seen since the fires, and the Office has asked for young people to help count them.

  The entire trip will last three hours. Bookings necessary.

Cost: Free                 When: May 8

Trip 2  Garland Valley

  Bring your drink and lunch for this walk in a beautiful area of the Blue Mountains. Garland Valley is close to the town of Garland but is part of the National Park. Many wild animals live in this area, including many rare birds. This is a great walk for bird-lovers. The trip lasts four hours. Bookings necessary.

Cost: ＄ 15                 When: May 8, May 15

Trip 3  Flashlight Adventure

  Put on your warm clothes, bring a flashlight and a pair of glasses, and come for a night walk along the Dungog Valley. A guide will lead the tour. Many of the animals you will see on this trip can only be seen at night. The guide will tell you about the lives of the animals you see. Numbers are strictly limited on night trips, so be sure to book early. This walk lasts two and a half hours.

Cost: ＄ 12               When: May 8, May 15, May 22

Equipment to be needed:

·   Please bring enough water and food for all walks.

·   Wear good walking shoes--no high heels.

·   Wear a hat for day walks.

·   Dress warmly for night walks.

·   Children must be with an adult.

·   Make sure your flashlight works well and bring extra batteries for night walks.

·   Follow all instructions from guides during the walks. The mountains are a dangerous place.

Bookings:

   Bookings for the above trips can be done by telephone (893 - 4847) or on the Internet at (www. Bluemountaintour.com)

1.Where are these trips?

A. In a large city.                                    B. In a park in the mountains.

C. In a special zoo.                                   D. In three different countries.

2.Which of the following is NOT necessary for the three trips?

A.A sleeping bag.                                   B. A pair of glasses.

C. Food and water.                                  D. Good walking shoes. 

3.What is the best title for the passage?

A. Adventure Travel in America

B. Hunting around the Great Mountains

C. Discovery Trips in the Blue Mountains

D. Interesting Trips in the East of the USA

 

查看答案和解析>>

科目：高中英語 來源：2014屆河北石家莊無極中學(xué)高三上學(xué)期第一次月考英語卷（解析版） 題型：閱讀理解

At night, bats fly through the air, catching hundreds of insects and other small animals. But during the day, they hardly move at all. Instead, bats pass the time hanging upside down from a secret spot.

There are a couple of reasons why bats rest this way. First of all, it puts them in a position for takeoff. Unlike birds, bats can’t fly into the air from the ground. Their wings don’t produce enough lift to take off from a dead stop, and their hind legs are so small and underdeveloped that they can’t run to build up the necessary takeoff speed. Instead, they use their front claws to climb to a high spot, and then fall into flight.

During the hours when most enemies are active, bats gather where few animals would think to look and most can’t reach. This allows them to disappear from the world until night comes again. There’s also little competition for these resting spots, as other flying animals don’t have the ability to hang upside down. Bats have a unique physiological adaptation that lets them hang around this way without using any energy. For you to hold your fist around an object tight, you contract(緊縮) several muscles in your arm, which are connected to your fingers by tendons(腱)；as one muscle contracts, it pulls a tendon, which pulls one of your fingers closed. A bat’s talons(爪) close in the same way, except that their tendons are connected only to the upper body, not to a muscle. To hang upside down, a bat pulls its claws open with other muscles. To get the talons to take hold of the surface, the bat simply lets its body relax. The weight of the upper body pulls down on the tendons connected to the talons, causing them to hold tight. Therefore, the bat doesn’t have to do anything to hang upside down.

1.Bats hang upside down because________.

A. they haven’t developed a pair of strong claws

B. they can’t start to fly from the ground directly

C. they have no hind legs to support their body

D. they can’t find quiet places to stay during the day

2.The third paragraph tells us that bats’ hanging upside down_______.

A. is to save their energy for night movement

B. is a way to fight against flying animals

C. is a great way to hide from danger

D. is a skill to compete for the flying places

3.Why can bats hang upside down easily?

A. Because their upper body is light.

B. Because they have strong muscles.

C. Because their talons are linked to muscles tightly.

D. Because their tendons are linked to their upper body.

4.What is the passage mainly about?

A. The living habits of bats.

B. How and why bats hang upside down.

C. The importance of bats’ hanging upside down.

D. How bats use their energy at night.

 

查看答案和解析>>

科目：高中英語 來源：2014屆浙江省臺州市高二下學(xué)期第一次月考英語試卷（解析版） 題型：閱讀理解

Harry is eighteen now. He studies in a middle school. His parents like him very much and hope he can become a famous man. So they often tell him to study hard and they do all for him. They call him at six in the morning, after breakfast his father takes him to school in a car and in the afternoon, as soon as the young man comes back, the supper is ready. Of course, he never washes his clothes or goes to buy something in the shops.

　  Once, Harry’s father was sent to London on business. He would stay there for half a year. Leaving, he told his wife to take good care of their son. The woman had to get up earlier and did all what her husband did before. And two months later she was so tired that she was ill in bed. Now the young man got into trouble. He couldn’t do any housework. He had to do as his mother told him. Even he didn’t know where to get on the bus!

　  Yesterday Harry’s mother found his shoes were worn out and told him to buy a new pair in the shop. But he didn’t know how to choose. The woman had a sigh(嘆息) and gave him a shoe pattern(鞋樣) and told him to buy a pair of shoes himself. It’s Saturday today and Harry doesn’t go to school. With a policeman’s help, he found a shop. The shopkeeper was friendly to him. The man brought a lot of shoes and asked him to choose. When he was trying on a pair, suddenly he remembered something and took them off. The man was surprised and asked, “What’s the matter, young man?”

　“I’m sorry, I’ve left the shoe pattern at home!”

1. _______ always does some housework in the morning.

A．Harry’s father     B．Harry’s mother    C．Harry             D．Nobody

2.Harry’s parents do all instead of him because _______.

A．he’s too young

B．he has poor health

C．he’s busy with his studies

D．they hope he spends all time on studies

3.The woman had to look after her son by herself because _______.

A．her husband wasn’t at home

B．she was stronger than her husband

C．she knew the young man well

D．she was freer than her husband

4. The woman told her son to buy a pair of shoes because _______.

A．she didn’t know what kind he needed

B．she was busy with the housework

C．something was wrong with her

D．she wanted her son to do something himself

5. In fact, _______.

A．Harry wanted his mother to buy shoes for him

B．Harry didn’t believe in himself

C．Harry wouldn’t listen to his mother

D．Harry was strong enough to buy shoes for himself

 

查看答案和解析>>

科目：高中英語 來源：2014屆山西省晉中市高二下學(xué)期期中考試英語試卷（解析版） 題型：閱讀理解

Welcome to one of the largest collections of footwear (鞋類) in the world that will make you green with envy. Here at the Footwear Museum you can see exhibits (展品) from all over the world. You can find out about shoes worn by everyone from the Ancient Egyptians to pop stars.

Room 1

The celebrity (名人) footwear section is probably the most popular in the entire museum. Stared in the 1950s there is a wide variety of shoes and boots belonging to everyone from queens and presidents to pop stars and actors! Most visitors find the celebrities’ choice of footwear extremely interesting.

Room 2

Most of our visitors are amazed and shocked by the collection of “special purpose” shoes on exhibition here at the Museum of Footwear. For example, there are Chinese shoes made of Silk that were worn by women to tie their feet firmly to prevent them from growing too much!

Room 3

As well as shoes and boots, the museum also exhibits shoe shaped objects. The variety is unbelievable. For example, there is a metal lamp that resembles a pair of shoes, and Greek wine bottles that look like legs!

The Footwear Library

People come from all over the world to study in our excellent footwear library. Designers and researchers come here to look up information on anything and everything related to the subject of footwear.

1. Where would you find a famous singer’s shoes?

A．Room 1.                              B．Room 2.

C．Room 3.                              D．The Footwear Library.

2.All exhibits in each room _____.

A．share the same theme

B．have the same shape

C．a(chǎn)re made of the same material

D．belong to the same social class

3.Which of the following is true according to the text?

A．Room 2 is the most visited place in the museum.

B．Researchers come to the Footwear Library for data.

C．The oldest exhibits in Room 1 were made in the 1950s.

D．Room 3 has a richer variety of exhibits than the other two.

4. The purpose of the text is to get more people to _____.

A．do research                           B．design shoes

C．visit the museum                        D．follow celebrities

 

查看答案和解析>>

同步練習(xí)冊答案