these trials, people are ________assigned to a "treatment" group, which benefits from the project, and a "control" group, which does not.

A. initially B. conventionally

C. superbly D. randomly

練習(xí)冊(cè)系列答案
相關(guān)習(xí)題

科目：高中英語(yǔ) 來(lái)源：2016屆北京海淀區(qū)高三上學(xué)期期中考試英語(yǔ)試卷（解析版） 題型：閱讀理解

Time Travel

If you could travel in time, where would you go? Perhaps you would watch an originalperformance of a Shakespeare’s play in Elizabethan England?

What about hanging out with Laozi in the Spring and Autumn Period? Or maybe you’d voyage far ahead of the present day to see what the future holds.

The possibility of time travel is indeed appealing. Stories exploring the subject have been around for hundreds of years. Perhaps the best known example is science fiction novel The Time Machine, which was written by H.G.Wells and published in 1895 for the first time. It was adapted into at least two feature films of the same name, as well as two television versions, and a large number of comic book adaptations. It is generally credited with the popularization of the concept of time travel using a vehicle that allows an operator to travel purposefully and selectively. The term “time machine”, coined by

Wells, is now universally used to refer to a vehicle transporting people into the far future.

But could time travel actually be possible? Some scientists say yes, in theroy. They propose using cracks in time and space called“wormholes”,which could be used as shortcuts to other periods．Einstein's theory of relativity allows time travel in extreme circumstances．And British physicist Stephen Hawking says you could travel into the future with a really fast spaceship—going at nearly the speed of light．Though building such a spaceship would of course be no simple task．

Even if you could travel into the past, there is something called the “grandfather paradox”．It asks what would happen if a time traveler were to go back in time and have his own grandfather killed for some reason, and therefore prevent himself from being born．If the time traveler wasn't born, how would he travel back in time？

And would you really like to visit the future？In H．G．Wells' book,the main character travels into distant time where he arrives at a beach and is attacked by giant crabs．He then voyages 30 million years into the future where the only living thing is a black object with tentacles（觸角）.

If that's what's in store, maybe we are better just living in the present day after all．

1.The novel The Time Machine mentioned in Paragraph 2 aims to show___________．

A．People's interest in time travel

B．the special feature of the book

C．the long history of time travel

D．the contribution of H．G．Wells

2.Einstein's and Hawking's theories_________．

A．have similarities in many ways

B．push the invention of the first spaceship

C．have proved wrong by some time travelers

D．suggest the possibility to invent the time machine

3.In Paragraph 4,“grandfather paradox”probably refers to the idea that__________．

A．the traveler is prevented from meeting his grandfather

B．the traveler goes back in time to seek for his grandfather

C．the grandfather's death makes the traveler's birth impossible

D．The reunion of the traveler and his grandfather brings happiness

4.According to the passage, what is probably the author's attitude towards time travel？

A．Unclear． B．Skeptical．

C．Supportive．D．Unconcerned．

查看答案和解析>>

科目：高中英語(yǔ) 來(lái)源：2016屆湖南衡陽(yáng)八中高一下學(xué)期期末考試英語(yǔ)試卷（解析版） 題型：單項(xiàng)填空

_____ is even important _____ as the earth cooled down, water began to appear on its surface.

A. That, which B. What, that

C. What, what D. It, that

查看答案和解析>>

科目：高中英語(yǔ) 來(lái)源：2016屆寧夏銀川市高三上學(xué)期統(tǒng)練一英語(yǔ)試卷（解析版） 題型：語(yǔ)法填空

閱讀下面材料，在空白處填入適當(dāng)?shù)膬?nèi)容（不多于3個(gè)詞）或括號(hào)內(nèi)單詞的正確形式，并把答案寫在答題卡上的相應(yīng)位置。

Louis invited his friends to lunch one day. He was cooking some delicious food in the kitchen. Suddenly, he 1. (find) that he had run out of salt. So Louis called to his son, “Go to the village and buy some salt, but pay a fair price for it: neither too much 2. too little.”

His son looked surprised. “I can understand why I shouldn’t pay too much, Father, but if I can pay less, 3. not save a bit of money?”

“That would be a very 4. (reason) thing to do in a big city, but it could destroy a small village like ours,” Louis said.

Louis’s guests, 5. had heard their conversation, asked why they should not buy sale more cheaply if they could. Louis replied, “The only reason why a man would sell sale 6. a lower price would be that he was desperate for money. And anyone who took advantage of that situation would be showing a lack of respect for the sweat and struggle of the man who worked very hard to produce 7. .”

“But such a small thing couldn’t 8. (possible) destroy a village.”

“In the beginning, there was only 9. very small amount of unfairness in the world, but everyone added a little, always 10. (think) that it was only small and not very important, and look where we have ended up today.”

查看答案和解析>>

科目：高中英語(yǔ) 來(lái)源：2016屆遼寧省大連市高三10月月考英語(yǔ)試卷（解析版） 題型：其他題

根據(jù)短文內(nèi)容，從短文后的選項(xiàng)中選出能填入空白處的最佳選項(xiàng)。選項(xiàng)中有兩項(xiàng)為多余選項(xiàng)。

Do you have a spare room in your house? Do you like to share your driveway in front of your garage with others? 1. Many people are benefiting from this new business of renting.

Perhaps the best-known example of a company in this field is Airbnb—an American web business which allows you to rent out your spare room to holidaymakers. It says it operates in 34,000 cities and it has 800,000 listings of rooms and apartments. 2.

A British company is doing something with parking spaces. Just Park’s founder，Anthony Eskinazi, says, “When I had the original idea. I spotted a driveway close to a spots stadium. It would have been so convenient if I could have just parked in that driveway rather than in a commercial car park.” 3. Around 20,000 people have advertised their spaces on the website, and he says around half a million drivers use it.

4. They are people who run things like traditional hotels and commercial car parks. They are afraid of ending up losing money.

5. Regulations for these new businesses are unclear. How will renting out your driveway affect your neighbor? Because this is a new business world, those rules aren’t there yet.

A. They seem to have occupied the majority of the market.

B. Both of these can help you make money.

C. And there is another problem.

D. And his great idea has proved a success.

E. But the new business of renting has its competitors.

F. There are many ways to earn money.

G. A commercial car park is inconvenient.

查看答案和解析>>

科目：高中英語(yǔ) 來(lái)源：2015-2016學(xué)年江西上高二中高二上第一次月考英語(yǔ)試卷（解析版） 題型：短文改錯(cuò)

短文改錯(cuò)（共10小題，每小題1分，滿分10分）

假定英語(yǔ)課上老師要求同桌之間交換修改作文，請(qǐng)你修改你同桌寫的以下作文。文中共有10處錯(cuò)誤，

句中最多有兩處。錯(cuò)誤涉及一個(gè)單詞的增加、刪除或修改。

增加：在缺詞處加一個(gè)漏詞符號(hào)（^），并在此符號(hào)下面寫出該加的詞。

刪除：把多余的詞用斜線（＼）劃掉。

修改：在錯(cuò)的詞下劃一橫線，并在該詞下面寫出修改后的詞。

注意：1．每處錯(cuò)誤及其修改均僅限一詞；

2．只允許修改10處，多者（從第11處起）不計(jì)分。

My dream school starts at 8:30 a.m and ends at 3:30 p.m. They are three lessons in the morning and two in the afternoon. We didn’t need to do so many homework. Therefore , we have more time with after-school activities. For example, we can do reading for one and a half hour and play sport for one hour every day.

My dream school look like a big garden. There are all kinds of the flowers and trees around the classroom buildings. We can lie on the grass for a rest, or sat by the lake listening music. The teachers here are kind and helpfully. They are not only our teachers but also our friends.

查看答案和解析>>

科目：高中英語(yǔ) 來(lái)源：2015-2016學(xué)年廣東湛江第一中學(xué)高二上期中英語(yǔ)試卷（解析版） 題型：短文改錯(cuò)

A concert was given to several famous singers last Saturday. Tickets were very hardly to get. Since I wanted to attend that concert, I bought one at the high price. For the first half an hour, the concert went on smooth. The nice shows of the singers were warmly welcomed by the audience, many of them couldn’t help burst into tears. Before long the microphone went wrong. Some people begin to make noise. The members of the theatre tried to keep in order, but failed. He had difficulty in continuing the concert. Thus, a perfectly good concert caused to be of no value by some uneducated people.

查看答案和解析>>

科目：高中英語(yǔ) 來(lái)源：2015-2016學(xué)年江蘇鹽城響水中學(xué)高二10月月考英語(yǔ)試卷（解析版） 題型：單項(xiàng)填空

I _________ returning to the train station and spending the rest of the day in the waiting room. Life is no fun without a companion to share it with.

A. ended up B. took up C. led to D. stick to

查看答案和解析>>

科目：高中英語(yǔ) 來(lái)源：2014-2015學(xué)年北京市西城區(qū)高三二模英語(yǔ)試卷（解析版） 題型：單項(xiàng)填空

—Is the project difficult for the students?

—No. Most of the relevant information ______ to them.

A. has been provided B. has provided

C. had been provided D. had provided

查看答案和解析>>

同步練習(xí)冊(cè)答案