题目内容

It is easier to float in the ocean than it is to float in a swimming pool. Do you know why?

Ocean water is full of salt— and salt water can hold up more weight than fresh water. See for yourself!

You Will Need:

● 3 cups of warm water

● Measuring cup

● Wide-mouthed jar

● Salt

● Spoon

● Raw potato

You Will Do:

1. Pour 1.5 cups of warm water into the jar.

2. Add 1/3 cup of salt.

3. Stir(搅拌) until the salt is completely dissolved.

4. Add another 1.5 cups of water. Pour it slowly over the back of the spoon into the jar so that the two liquid will not mix together.

5. Gently place the potato into the jar. Do not drop it.

What Will Happen:

The potato will sink— but only halfway!

Why?

Salt water is heavier than fresh water, so it will stay on the bottom. The fresh water will remain on top.

The potato is heavier than the fresh water, but it is lighter than the salt water. That is why the potato will sink halfway down.

1.In which step of the experiment do you add the salt?

A. Step 1. B. Step 2.

C. Step 3. D. Step 4.

2.In Step 4 of the experiment, why do you pour the water over the spoon “slowly”?

A. It is easier to see what you are doing.

B. It pushes the fresh water to the bottom.

C. It will keep the water from coming out.

D. It will keep the liquids from mixing together.

3.In the experiment, what should you do right after you pour the water over the spoon?

A. Add the salt to the water. B. Stir the salt into the water.

C. Place the potato in the jar. D. Pour warm water into the jar.

练习册系列答案
相关题目
20．


21．If you want to have a guitar lesson，you mayA．
A．surf the website：www．music．com
B．call Susan at 7328059
C．telephone Mr．White at 5132683
D．email sdgt@yahoo．com
22．Who is the owner of the lost dog？B
A．Mr．White．B．Susan．C．Larry．D．David．
23．If you want the job as a taxi driver，you shouldC．
A．master at least three languages
B．younger than 50
C．know the city very well
D．be an inexperienced driver
24．Which information about the apartment is not mentioned in the table？B
A．It has a beautiful view．
B．It has three floors．
C．It has hot water in the daytime．
D．It has a kitchen．

An absolute description of the threat hanging over the world's mammals,reptiles,amphibians and other life forms has been published by the well-known scientific journal,Nature.A special analysis carried out by the journal indicates that an astonishing 41% of all amphibians on the planet now face extinction while 26% of mammal species and 13% of birds are similarly threatened.

Many species are already critically endangered and close to extinction,including the Sumatran elephant,Amur leopard and mountain gorilla.But also in danger of vanishing（消失）for the wild,it now appears,are animals that are currently rated as merely being endangered.

In each case,the finger of blame points directly at human activities.The continuing spread of agriculture is destroying millions of hectares of wild habitats every year,leaving animals without homes,while the introduction of newly-come species,often helped by humans,is also damaging native populations.At the same time,pollution and overfishing are destroying ocean ecosystems.

"Habitat destruction,pollution or overfishing either kill off wild creatures and plants or leaves them badly weakened," said Derek Tittensor,an ocean ecologist at the World Conservation Monitoring Centre in Cambridge. "The trouble is that in coming decades,the additional threat of worsening climate change will become more and more common and could then kill off these survivors."

The problem,according to Nature,is worsened because of the huge gaps in scientists knowledge about the planet's biodiversity.Evaluations of the total number of species of animals and plants alive vary from 2 million to 50 million.In addition,evaluations of current rates of species' disappearances vary from 500 to 36,000 a year. "That is the real problem we face," added Tittensor. "The scale of uncertainty is huge."

In the end,however,the data indicate that the world is heading cruelly towards a mass extinction-which is defined as one involving a loss of 75% of species or more.This could arrive in less than a hundred years or could take a thousand,depending on extinction rates.

1.What's the main idea of the first two paragraphs?

A. Figures about some wild animals are astonishing.

B. Nature is the famous journal around the world.

C. Many endangered species are close to extinction.

D. Some rare species have appeared around the world.

2.From paragraph 4 we know that another future threat is .

A. destruction of habitats B. overfishing and pollution

C. the worsening climate change D. killing off wild creatures and plants

3.What is the real problem we are facing now according to paragraph 5?

A. The killing of wild creatures and cutting of trees.

B. The global warming caused by human beings.

C. The destruction of ocean ecosystem by pollution.

D. Evaluation of current rates of species' disappearances.

4.What does "This" in the last sentence refer to?

A. mass extinction. B. extinction rates.

C. extinction time. D. 75% of species or more.

Remembering names is an important social skill. Here are some ways to master it.

Recite and repeat in conversation.

When you hear a person’s name，repeat it. Immediately say it to yourself several times without moving your lips. You could also repeat the name in a way that does not sound forced or artificial.

Ask the other person to recite and repeat.

You can let other people help you remember their names. After you’ve been introduced to someone，ask that person to spell the name mad pronounce it correctly for you. Most people will be pleased by the effort you’re making to learn their names.

Admit you don’t know.

Admitting that you can’t remember someone’s name can actually make people relaxed. Most of them will feel sympathy if you say. “I’m working to remember names better. Yours is right on the tip of my tongue. What is it again?”

Use associations.

Link each person yon meet with one thing you find interesting or unusual. For example，you could make a mental note:“Vicki Cheng -- tall, black hair.” To reinforce your associations, write them on a small card as soon as possible.

Limit the number of new names you learn at one time.

When meeting a group of people, concentrate on remembering just two or three names. Free yourself from remembering every one. Few of the people in mass introductions expect you to remember their names. Another way is to limit yourself to learning just first names. Last names can come later.

Go early.

Consider going early to conferences, parties and classes. Sometimes just a few people show up on time. That's fewer names for you to remember. And as more people arrive, you can hear them being introduced to others—an automatic review for you.

1.How will most people feel when you try hard to remember their names?

A. They will be moved. B. They will be annoyed.

C. They will be delighted. D. They will be discouraged.

2.When you meet a group of people, it is better to remember __

A. all their names B. a couple of names first

C. just their last names D. as many names as possible

3.What does the text mainly tell us?

A. Tips on an important social skill.

B. Importance of attending parties.

C. How to make use of associations.

D. How to recite and repeat names.

I was in Houston a few weeks ago, and needed to be back home in Austin by the early morning the next day. So I ________ to leave that morning. ________ my tire blew out on the way. I ________ a small parking lot. Then I ________ the doors and picked up my phone to call a tow truck (拖车). Soon a man ________ on my driver’s side window and asked if he could help me. From his ________ and behavior, I knew he was far more ________ to rob than help me, so I ________ refused and told him the tow truck was due any minute. He asked again, but again I gently shook my head. He finally said, “Ma’am, you need ________. A tow truck in Houston will arrive anywhere between 45 minutes and almost ________ (which I knew was true), and you are not going anywhere until you have that tire ________.”

I looked hard, straight into his ________, and instinctively (凭直觉) saw someone different from the ________ person he appeared to be at first sight. So, against all reasonable ________, but trusting my instincts, I got out. He looked ________, but got right to work, trying to find the ________ tire. It took a while ________ it was stored under the seat.

He changed the tire, ________ the seat to its place and said, “Thank you for letting me help you. You gave me a ________ when most people would never open the door to someone like me. Would it be okay if I gave you a hug?” When I recovered, I gave him a giant hug. I left with a new tire and a renewed ________ in human nature.

1.A. wanted B. happened C. hoped D. had

2.A. Amazingly B. Mostly C. Strangely D. Unfortunately

3.A. pulled into B. walked around C. broke into D. looked at

4.A. opened B. fixed C. locked D. broke

5.A. hit B. knocked C. climbed D. checked

6.A. mood B. personality C. height D. appearance

7.A. willing B. friendly C. likely D. pleased

8.A. repeatedly B. badly C. politely D. hurriedly

9.A. money B. water C. gas D. help

10.A. never B. now C. forever D. already

11.A. balanced B. changed C. moved D. sold

12.A. mind B. eyes C. head D. heart

13.A. worried B. wise C. cold-hearted D. unreliable

14.A. arguments B. judgments C. decisions D. selections

15.A. devoted B. disappointed C. surprised D. frightened

16.A. flat B. free C. spare D. worn

17.A. so B. but C. once D. since

18.A. returned B. left C. held D. showed

19.A. lesson B. chance C. gift D. job

20.A. pride B. delight C. faith D. interest

We already know the fastest, least expensive way to slow climate change: Use less energy. With a little effort, and not much money, most of us could reduce our energy diets by 25 percent or more—doing the Earth a favor while also helping our wallets.

Not long ago, my wife, PJ, and I tried a new diet—not to lose a little weight but to answer an annoying question about climate change. Scientists have reported recently that the world is bending up even faster than predicted only a few years ago, and that the consequences could be severe if we don't keep reducing emissions(排放) of carbon dioxide (CO2 ) and other greenhouse gases that are trapping heat in our atmosphere.

We decided to try an experiment. For one month we recorded our personal emissions of CO2. We wanted to see how much we could cut back, so we went on a strict diet. The average US household(家庭) produces about 150 pounds of CO2 a day by doing common-place things like turning on air-conditioning or driving cars. That's more than twice the European average and almost five times the global average, mostly because Americans drive more and have bigger houses. But how much should we try to reduce?

For an answer, I checked with Tim Flannery, author of The Weather Makers: How Man is Changing the Climate and What it Means for Life on Earth. In his book, he had challenged readers to make deep cuts in personal emissions to keep the world from reaching extremely important tipping points, such as the melting(融化) of the ice sheets in Greenland or West Antarctica. "To stay below that point, we need to reduce CO2 emissions by 80 percent," he said.

Good advice, I thought. I'd opened our bedroom windows to let in the wind. We'd gotten so used to keeping our air-conditioning going around the clock. I'd almost forgotten the windows even opened. We should not let this happen again. It's time for us to change our habits if necessary.

1.Why did the author and his wife try a new diet?

A. To take special kinds of food.

B. To respond to climate change.

C. To lose weight.

D. To improve their health.

2.The underlined words "tipping points" most probably refer to ________.

A. freezing points B. burning points

C. melting points D. boiling points

3.It can be inferred from the passage that ________.

A. it is necessary to keep the air-conditioning on all the time

B. it seems possible for every household to cut emissions of CO2

C. the average US household produces about 3,000 pounds of CO2 a month

D. the average European household produces about 1,000 pounds of CO2 a month

Chengdu, capital city of southwestern China's Sichuan province, 1.（name）one of the top 10 ancient capitals in China at a conference 2.(hold) on Oct. 25th. 2016. Along with Chengdu, nine other cities, including Beijing, Xi'an, Nanjing and Luoyang, 3. (be) also on the list.

As one of the cradles (摇篮) of Chinese civilization, Chengdu has a history of more than 4,500 years. It is one of the 4.(old) cities in China, even in the world, having been the capital of five major states. 5. addition, Chengdu has done a good job preserving 6. (it) history. The location, name and center of the city have never been changed, which reflects 7. (clear) the city's vitality (活力）and cultural identity.

"Chengdu has its unique spirit, related to inclusiveness and independence," said the president of an 8.(associate) of ancient Chinese capital studies. "Chengdu is 9. open and influential city in Chinese history. So there is no doubt 10.it is an important and famous capital."

People can be addicted to different things, e.g. alcohol, drugs, certain foods, or even television. People who have such an addiction are compulsive, i.e they have a very powerful psychological need that they feel they must satisfy. According to psychologists, many people are compulsive spenders; they feel that they must spend money. This compulsion, like most others, is irrational-impossible to explain reasonably. For compulsive spenders who buy on credit, charge accounts are even more exciting than money. In other words, compulsive spenders feel that with credit, they can do anything. Their pleasure in spending enormous amounts is actually greater than the pleasures that they get from the things they buy.

There is even a special psychology of bargain hunting. To save money, of course, most people look for sales, low prices, and discounts. Compulsive bargain hunters, however, often buy things that they don’t need just because they are cheap. They want to believe that they are helping their budgets, but they are really playing an exciting game: when they can buy something for less than other people, they feel that they are winning. Most people, experts claim, have two reasons for their behavior: a good reason for the things that they do and the real reason.

It is not only scientists, of course, who understand the psychology of spending habits, but also business people. Stores, companies and advertisers use psychology to increase business: they consider people’s need for love, power, or influence, their basic values, their beliefs and opinions, and so on in their advertising and sales methods.

Psychologists often use a method called “behavior therapy” to help individuals solve their personal problems. In the same was, they can help people who feel that they have problems with money.

1.According to psychologists, a compulsive spender is one who spends large amounts of money ________.

A. and takes great pleasure from what he or she buys

B. in order to satisfy his or her basic needs in life

C. just to meet his or her strong psychological need

D. entirely with an irrational eagerness

2.The passage is mainly concerned with ________.

A. the psychology of money - spending habits

B. the purchasing habits of compulsive spenders

C. a special psychology of bargain hunting

D. the use of the psychology of spending habits in business

3.Which of the following statements is true?

A. All people spend money for exactly the same reason they need to buy things.

B. Business people and advertisers can use the psychology of money to increase sales.

C. Business people understand the psychology of compulsive buying better than scientists do.

D. Compulsive bargain hunters do not have problems with money.

4.From the passage we may safely concluded that compulsive spenders or compulsive bargain hunters ________.

A. are really unreasonable

B. need special treatment

C. are really beyond treatment

D. can never get any help to solve their problems with money

假定英语课上老师要求同桌之间交换修改作文, 请你修改你同桌写的以下作文。文中共有10处语言错误，每句中最多有两处。每处错误仅涉及一个单词的增加、删除或修改。

增加：在缺词处加一个漏词符号（∧），并在其下面写出该加的词。

删除：把多余的词用斜线（＼）划掉。

修改：在错的词下划一横线，并在该词下面写出修改后的词。

注意：1. 每处错误及修改均仅限一词；

2. 只允许修改10处，多者（从第11处起）不计分。

My brother Donald didn’t do well in math. When the day of the exam comes, Donald sat next to Brian, which was always good at math. Donald careful copied Brian’s answers. At end of the exam, the teacher collected the papers and graded it. Then she decided to give a prize to the student who got the high grade. But it was a bit of difficult for her to make a decision, because Donald and Brian got the same grade. The teacher thought about that and made on her mind to give the prize to Brian. Donald said it was unfair. “That’s true,” the teacher said. “Therefore, Brian’s answer to Question 18 was ‘I don’t know’. Your was ‘Neither do I’.”

违法和不良信息举报电话：027-86699610 举报邮箱：58377363@163.com

精英家教网