Everyone can play an important role in the so...

Everyone can play an important role in the society. As members, we should try our best to do________.

A.what we should do B.what shuuld we do

C.how we should do D.how we should do

九年级英语单选题中等难度题查看答案及解析

Everyone can play an important part in society. As members, we should try our best to do __　　　 .

A. how we should do　　　　　　　　　　　　　　 B. what should we do

C what we should do　　　　　　　　　　　　　　　　 D. how should we do

九年级英语单项填空困难题查看答案及解析

Everyone plays an important part in society.　 As members, we should try our best to do

　　　　 to make the world better and better.

A. what we should do

B. what should we do

C. how we should do

九年级英语单选题困难题查看答案及解析

Bacterial Quorum Sensing

Bacteria(细菌)play an important role in our lives. They can keep us alive as well as make us sick. It wasn’t until fairly recently that we learned bacteria can communicate with one another.

In the 1960s, researchers found that a kind of bacteria called Vibrio fischeri（费氏弧菌） produced no light when they were alone, but that they exhibited great amount of light as the bacterial population grew to a certain number. How did this happen? How can Vibrio fischeri tell the difference between times when they’re alone and times when they’re in a community, and then all do something together?

Researchers found they talk to each other with a chemical language—signal molecules(信号分子). Vibrio fischeri makes signal molecules, and it also has a receptor on its surface that fits like a lock and key with a signal molecule. As the bacteria increase, more and more signal molecules are sent into the environment. When signal molecules increase to a certain amount, they lock down into those receptors and information comes into the bacteria, which tells them how many neighbors there are. As soon as they realize the population has hit the certain number, all of the bacteria behave as a group, making light together. In the past ten years, researchers have found all bacteria have systems like this: they make and recognize chemical words, determine(判断)the size of the community, and carry out tasks that would be unsuccessful if a single one were to act alone. This process is called quorum sensing.

Most of the time, bacteria live with thousands of other species (种类)of bacteria. There has to be a language of interspecies communication. In fact, bacteria have another kind of signal molecule, which is the common language used by all species. Moreover, this kind of molecule has its own receptor. In this way, bacteria are able to count different populations, and then they decide what task to carry out depending on which species has the greatest population.

Knowing how bacteria communicate could influence how we fight disease. What if bacteria can’t talk or hear? They won’t recognize when there are enough bacteria and when to exhibit the group behavior to make us sick. Researchers are developing a method—to make molecules that look like the real ones and then they lock into the receptors to jam recognition of the real situation.

On the other hand, researchers also improve the conversation of the beneficial bacteria, so they can do things that we want them to do better than they would do on their own.

1.According to the passage, what can we learn about quorum sensing?

A.Quorum sensing may happen when there is only one Vibrio fischeri.

B.Signal molecules are kept away from receptors during quorum sensing.

C.Most bacteria have similar systems to make light during quorum sensing.

D.Bacteria carry out a group task when their population hit a certain number.

2.What can we learn from the passage?

A.The more species there are, the more group actions bacteria will take.

B.In different environments, bacteria have different interspecies languages.

C.Beneficial bacteria communicate better by themselves than harmful ones.

D.To fight disease, researchers try to turn off the communication between harmful bacteria.

3.The passage is mainly about ________.

A.why bacterial population grows B.how bacteria communicate with each other

C.which bacteria help fight disease D.what scientists do to find quorum sensing

九年级英语阅读单选中等难度题查看答案及解析

Everyone has an important role in society. In this time of public crisis（危机）, it’s important that each of us sticks to our roles and plays them well. What can common people do in this crisis? How are the Chinese people taking on their special responsibilities? Here are some of the examples.

The novel coronavirus（新冠病毒）made this year’s Spring Festival very different for most of us. Many places in China began a first-level emergency (突发事件) response to the virus at the end of January, calling for people to stay at home. Following these rules, most people gave up family dinners during the Spring Festival and canceled any festival celebrations.

“It’s the quietest Chinese New Year I’ve ever had,” Xin Jingrong, a 14-year-old student from Nanning, Guangxi. It was the first time that Xin’s grandmother had to put off her trip to Nanning and stay alone in her hometown.

The control all over China not only separates many families, but also　　　　　 ▲　　　　 . Many shops are closed, delivery services are slow, and wearing masks in public has become a must. But people are showing their understanding and cooperation (合作).

Tong Zexi, a 15-year-old student from Harbin, has not gone out in more than 20 days. “I know I need to protect myself and cause no trouble. In this key time, when one gets sick, many others could be influenced.”

More than simply following the rules, some people have done amazing things to help fight the outbreak. On Feb 3, Zhao Junyan, a Junior 2 student from Shanghai, brought 15,000 masks from Indonesia back to China, People’s Daily reported. Zhao, while traveling in Jakarta, collected the masks with his uncle, who works in the city. The 15-year-old gave away all of the masks to Cangnan, Zhejiang, his hometown. “When a country is in trouble, everyone is responsible to help,” Zhao said to the reporter. “What I have done is what an normal Chinese person can possibly do.”

As a popular speech says nowadays, “We are all fighters!” Everyone has his or her role to play in this fight. And it’s believed that we can soon enjoy the warm sunshine and beautiful spring freely outside!

1.What do we know about Xin Jingrong?

A.Xin lives in Nanjing. B.Xin’s grandmother celebrated this Spring Festival alone.

C.Xin is a quiet person. D.Xin’s grandmother was unable to go back to her hometown.

2.In the fourth paragraph,which of the following sentence can be put in the 　　 ▲　　　　　　 .

A.cheers up many people B.makes the world more colorful

C.makes daily life inconvenient D.brings fears to people

3.If we put the passage into three parts, which of the following is the best?

(①=para.1 ②=para.2 ③=para.3 ④=para.4 ⑤=para.5 ⑥=para.6 ⑦=para.7)

A.①②③;④⑤⑥;⑦ B.①;②③④⑤⑥;⑦

C.①②;③④⑤;⑥⑦ D.①;②③④;⑤⑥⑦

4.The story is mainly about________.

A.what teenagers do to enjoy themselves at home in the crisis

B.what Chinese people do to take on their responsibilities in the crisis

C.how Chinese New Year was celebrated this year during the Spring Festival

D.how common people’s lives are changed by the virus in the crisis

九年级英语阅读单选中等难度题查看答案及解析

As a student, books play an important role in our life. As Gorky once said, “Books are the ladder of human progress.” Then which book is your favorite?

As a book lover, my favorite book is Robinson Crusoe. This book is 1.（写）by Daniel Defoe, and it has already 2.（影响）lots of students like me. Every time I read it, I see a tall and strong image of Robinson. The 3.（整个的）book tells the stories of his adventures and courage. He is such a brave man that I4.(钦佩) him so much. When Robinson was young, he dreamt of sailing on the sea day and night. Unfortunately, after his grown up, he 5.（实际上）lived on a desert island for twenty-eight years. He6.（经受）a lot. But the idea of 7. up（放弃）never came to his mind. During these years, he had to endure hunger, fight against 8.（自然的）disasters, and overcome many 9.（困难）. But the great man went out of the desert island at last because of his fighting 10.（精神）, and hard-working attitude. That story encouraged me deeply. Our life cannot be lucky all the time. But no pains no gains. And only hard work can lead us to a better life.

九年级英语单词填空困难题查看答案及解析

Sun Li, who played the lead role in Nothing Gold Can Stay《那年花开月正圆》, says “As an actress, you can’t be _________ hard-working.”

A. very　　 B. so　　 C. too　　 D. that

九年级英语单选题中等难度题查看答案及解析

Zhao Liying, who played the lead role in Journey of Flowers, says “As an actress, you can never be_______ hard-working.”

A. so　　 B. such　　 C. enough　　 D. too

九年级英语单选题中等难度题查看答案及解析

Smart phones play an important role now. As long as we take them，we can ______ many problems easily.

A.deal with B.stick to C.cut off

九年级英语单选题中等难度题查看答案及解析

Music plays an important role in our lives. We can hear music everywhere. We can't live _______ it. At the same time, music can ________our feelings. Different kinds of music can influence us in different ways.　　

Music makes you relax.

When you have too much ______with your study, you can listen to music for a while.

Soon you can feel relaxed. Studies show that customers would like to stay there longer when stores play relaxing music. Then they will______buy more things. So many stores try to play music that their customers enjoy.　　

Music is a healer（治愈师）.

When you feel sad, music can comfort you. Then you can feel more confident about life and your problems. When you have difficulty with sleep, some______ music can help you fall asleep easily. A group of teenagers________had depression(抑郁症）shared their favorite songs with each other. Each teenager explained why he or she liked the song. After talking about it, the teenagers said they felt__________.

Music helps you to learn.

Scientists find that you can improve your memory and intelligence______ listening to music. Don Campbell, an expert, believes music can make people,______ babies, stronger, happier, smarter and more creative. Some experts_______playing light music to help you pay attention when you are studying.　　

No matter what style of music you like, you can use it to help you.

1.A.on B.with C.without

2.A.support B.change C.keep

3.A.fun B.stress C.pleasure

4.A.possibly B.impossibly C.painfully

5.A.noisy B.loud C.soft

6.A.which B.that C.what

7.A.better B.sadder C.sicker

8.A.after B.before C.during

9.A.except B.nearly C.even

10.A.suggest B.avoid C.remain

九年级英语完型填空简单题查看答案及解析