题目内容
A.How do you study for a test?
B.I’m afraid of the dark.
C.I can choose my clothes.
Life, in_________ (普遍的), as many things we do, has never been easy.
—Why didn’t you come to my birthday party, Sally?
—Sorry, I was so busy that I _______ forgot it.
A.luckily B.completely C.hardly D.clearly
There will be heavy rain and strong wind next ___________ / wi:k /.
A.week B.wait C.west D.weak
A. B. C.
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
Tony and I________table tennis once a week. He plays better than I do.
A.play B.will play C.played D.have played
Hong Kong is a city that's full of surprises. 40% of the land________ beaches, woodlands (林地) and mountains. Hong Kong is a water city ______ different islands, and kids will have fun_________boats everywhere.
You can also________a lot of nice food there. You can walk into Dim Sum restaurants at any time. They are always ________, noisy and full of families. After you sit down at a big round table, you may_______ for waitresses to come with ________dishes. As they come by, tell them the dishes you want. The waitress will put the dishes down on your table. Keep asking for dishes until you are________ .
Hong Kong has________ shopping areas, and the Jade (玉) Market in Kowloon is a good place. Here, you can_________ jade earrings, jewelry and carved (雕刻的) animals, such as tigers and dragons.
1.A.is B.are C.was
2.A.at B.of C.with
3.A.going B.taking C.riding
4.A.cook B.eat C.make
5.A.busy B.free C.quiet
6.A.stop B.wait C.look
7.A.same B.terrible C.different
8.A.full B.hungry C.thirsty
9.A.many B.much C.a little
10.A.get back B.leave for C.find
New rules and behavior standards (行为规范) for middle school students came out. Who are the most excellent students? Middle schools use a new way to decide that. The best students won't only have good grades. They will also be the kids who don't dye (染) their hair, smoke or drink. The following are some of the new rules.
Tell the truth. Have you ever copied others' work during an exam? Don't do it again. That's not what an honest student should do. If you played computer games for two hours in your room, don't tell your parents you were doing your homework.
Do more at school. Good students love animals and care about others. April is Bird-Loving Month in China. Is your school doing anything to celebrate it? You should join! That way, you can learn more about animals and learn how to protect them. And when your classmates are in trouble, remember to give them a hand. A friend in need is a friend indeed.
Use the Internet carefully. Try to keep away from web pages that are bad for you. Find good websites and use them for homework.
Be open to new ideas. Have you ever thought that people could live on the moon? Maybe you can discover a new planet someday. Don't look down on new ideas. You should welcome them because new ideas can make life better.
1.Middle schools use a new way to decide ________ the most excellent students are.
2.It's not honest to __________others' work during an exam.
3.Which sentence means"患难见真情"in the third paragraph?
_____________________
4.New ideas can make your life better, so ____________________.
5.How many rules are mentioned to be the most excellent students?
B.
C.