If you could change your child's DNA in the future to protect them against diseases, would you? It could be possible because of technology known as CRISPR- Cas, or just CRISPR.
CRISPR involves a piece of RNA, a chemical messenger, designed to work on one part of DNA； it also uses an enzyme (If) that can take unwanted genes out and put new ones in, according to The Economist. There are other ways of editing DNA, but CRISPR will do it very simply, quickly, and exactly.
The uses of CRISPR could mean that cures are developed for everything from Alzheimer's to cancer to HIV. By allowing doctors to put just the right cancer-killing genes into a patient's immune system, the technology could help greatly.
In April scientists in China said they had tried using CRISPR to edit the genomes (基因组)of human embryos. Though the embryos would never turn into humans, this was the first time anyone had ever tried to edit DNA from human beings. With this in mind, the US' National Academy of Sciences plans to discuss questions about CRISPR s ethics(伦理问题).For example? CRISPR doesn't work properly yet. As well as cutting the DNA it is looking for, it often cuts other DNA, too. In addition, we currently seem to have too little understanding of what DNA gives people what qualities.
There are also moral questions around playing God”. Of course, medicine already stops natural things from happening-for example, it saves people from infections. The opportunities to treat diseases make it hard to say we shouldn't keep going.
A harder question is whether it is ever right to edit human germ-line(种系)cells and make changes that are passed on to children. This is banned in 40 countries and restricted in many others. However, CRISPR means that if genes can be edited out, they can also be edited back in. It may be up to us as a society to decide when and where editing the genome is wrong.
Also, according to The Economist, gene editing may mean that parents make choices that are not obviously in the best interests of their children: “Deaf parents may prefer their children to be deaf too； parents might want to make their children more intelligent at all costs.
In the end, more research is still needed to see what we can and can't do with CRISPR. “It's still a huge mystery how we work,” Craig Mello? a UMass Medical School biologist and Nobel Prize winner, told The Boston Globe, "We're just trying to figure out this amazingly complicated thing we call life.
1.What is the passage mainly about?
A.What we can and can't do with CRISPR.
B.How CRISPR was developed by scientists.
C.The advantages of CRISPR and arguments about its ethics.
D.Scientists' experiments of using CRISPR to edit human embryos.
2.According to the passage, the technology of CRISPR .
A.is very safe because it only cuts the DNA it is looking for
B.is banned in most countries and restricted in many others
C.could cause parents to make unwise choices for their children
D.could help us discover the link between DNA and the qualities it gives people
3.It can be inferred from the passage that .
A.all diseases could probably be cured through the uses of CRISPR
B.scientists had never edited genomes before CRISPR was invented
C.CRISPR is a technology that uses an enzyme to work on RNA and DNA
D.CRISPR has proven to be the most effective way to protect children against diseases
4.What is the author's attitude towards CRISPR?
A.Supportive. B.Worried. C.Negative. D.Objective.
A black hole is created when a large star burns out. Like our sun, stars are unbelievably hot furnaces(熔炉)that burn their own matter as fuel. When most of the fuel is used up, the star begins to die.
The death of a star is not a quiet event. First there is a huge explosion. As its outer layer is blasted off into space, the dying star shines as brightly as a billion suns.
After the explosion gravity pulls in what's left of the star. As the outside of the star sinks toward the center, the star gets smaller and smaller. The material the star is made of becomes tightly packed together. A star is so dense that a teaspoon of matter from it weighs billion of pounds.
The more the star shrinks, the stronger the gravity inside it becomes. Soon the star is very tiny, and the gravity pulling it in is unbelievably strong. In fact, the gravity is so strong that it even pulls light into the star! Since all the light is pulled in, none can flee. The star becomes black when there is no light. Then a black hole is born!
That's what we know about black holes. What we don't know is this: What happens inside a black hole after the star has been squeezed into a tiny ball? Does it keep getting smaller and smaller forever? Such a possibility is hard to imagine.
But if the black hole doesn't keep shrinking, what happens to it? Some scientists think black holes are like doorways to another world. They say that as the star disappears from our universe, it goes into another universe. In other words a black hole in our universe could turn into a “white hole” in a different universe. As the black hole swallows light, the white hole shines brightly-somewhere else. But where? A different place, perhaps, or a different time-many years in the past or future.
Could you travel through a black hole? Right now, no. Nothing we know of could go into a black hole without being crushed. So far the time being, black holes must remain a mystery.
Black holes are a mystery-but that hasn't stopped scientists from dreaming about them. One scientist suggested that in the future we might make use of the power of black holes. They would supply all of Earth's energy needs, with plenty to spare. Another scientist wondered if a black hole could some day be used to swallow earthly waste-a sort of huge waste disposal(处理)in the sky!
1.When the star begins to die, .
A.there is no fuel left in it
B.its outer layer goes into space first
C.it will explode and then become smaller
D.it doesn't give off light any longer
2.Which of the following doesn't help produce a black hole?
A.The star becomes very tiny and dense.
B.The light can't go out of the star.
C.The gravity inside the star is very strong.
D.The dying star shines very brightly.
3.What can we know from the passage?
A.A star will blast and die when it lacks fuel to support its burning.
B.A black hole can swallow everything because it becomes smaller all the time.
C.Man can never travel through a black hole but can make use of its power.
D.Scientists have found that a black hole goes into another universe and becomes a white hole.
4.What's the best title for this passage?
A.A New Scientific Discovery: Black Holes
B.How Do Black Holes Come into Being?
C.What Are Black Holes?
D.Travel Through A Black Hole
I am the proud owner of three pet dogs. Over the years, I have watched their behaviours carefully that help me when I travel around the world.
One important lesson that my dog, Cody, taught me is how to deal with little problems in life. From his calm behavior when someone knocked unexpectedly at the door to the indifferent way he has dealt with his recent serious illness, he has always had the same easy-going attitude. This attitude is an important lesson to me in how I can face difficult situations when travelling, I've learned to try to handle bad situations calmly, such as when we miss a train? lose luggage? and so on.
Another dog of mine, Preston, loves to walk around the yard, spending hours smelling every place and finding out what it means to him. Taking it slowly is another lesson that's been very hard for me to learn. As an active traveller, I am actually experiencing less by speeding through everything, rather than slowly getting to know a place. Even if it means that you won't see as many things, going slowly when you travel is the only way to really get to know a new place. Rushing around a foreign city isn't fun at all.
My dog, Moya, came from a truly bad situation. I am not sure what happened to her before； I just know it wasn't good. And while she has become more relaxed over the years, she is still slightly on edge. She is very cautious when faced with any new situation. But once she's accustomed to her new surroundings, she is fine. She doesn't let fear influence her experience. The same can be applied to our travel experience. No matter where we go, we need to manage new situations with caution--while at the same time not letting that caution turn into fear.
Many thanks to my pets. Truly speaking, pets are as basic to American culture as hot dogs or apple pies. To Americans, pets are not just property, but a part of the family. After all, pets are people, too, with the help of whom I am able to gain a lot and live differently.
1.One of the three dogs, Cody,_______ .
A.once suffered from a serious illness
B.is excited when under pressure
C.enjoys walking around the yard
D.is unable to deal with new situations
2.From Preston, the author learned that one should ______.
A.pay attention to the details in life
B.try to see as many things as possible when travelling
C.stay indifferent to strangers
D.travel around slowly and have fun
3.The underlined phrase "on edge" in the fourth paragraph probably means “_____ ”.
A.hungry B.nervous C.calm D.angry
4.Which of the following best shows the structure of the passage?
A.
B.
C.
D.
Teacher, Foreign Language (High School)
DoDEA offers teaching opportunities in some of the most amazing and culturally rich places in the world. Come and work for the Department of Defense Education Activity (DoDEA) schools !
Salary: US$ 39,775-US $ 80,930 Per School Year
Open Period: 10/3/2019 to 7/31/2020
Department: Department of Defense
Agency: Department of Defense Education Activity
Position Info: Flexible Schedules, Flexible Appointment Types
Who may apply: US Citizens； prior teaching experience is required
Food Inspector
The Food Safety and Inspection Service (FSIS) is the public health agency in the US Department of Agriculture responsible for ensuring that the nation's commercial supply for meat, poultry and egg products is safe, wholesome and correctly labeled and packaged.
Salary: US $ 31,628-US $ 50,932 Per Year
Open Period: 7/18/2019 to 7/17/2020
Department: Department of Agriculture
Agency: Food Safety and Inspection Service
Position Info: Full-time, Permanent
Who may apply: US Citizens； graduates in Food Quality and Safety are preferred
Supervisory Public Health Veterinarian(兽医)
This is an excellent opportunity to seek a greater leadership role and responsibility in public health. If you are a new, mid-career, or experienced professional interested in a Public Health Veterinarian (PHV) career, this job is for you!
Salary: US$ 57,928-90,344 Per Year
Open Period: 9/30/2019 to 9/30/2020
Department: Department of Agriculture
Agency: Food Safety and Inspection Service
Position Info: Full-time, Permanent
Who may apply: US Citizens and Nationals； no prior Federal experience is required
Veterinary Medical Officer-Veterinarian
The National Animal Health Emergency Response Corps (NAHERC) assists in the federal response to domestic (国内)and international animal disease outbreaks, threats, or natural disasters.
Salary: US $ 27. 78-US $ 36. 12 Per Hour
Open Period: 5/9/2019 to 5/1/2020
Department: Department of Agriculture
Agency: Animal and Plant Health Inspection Service
Position Info: Full-time, Permanent
Who may apply: US Citizens and Nationals； no prior Federal experience is required
1.If you apply to be a teacher in DoDEA, you .
A.should have a good command of foreign cultures
B.will be able to arrange work time flexibly
C.should work for the Department of Agriculture
D.can send in your application from July 2019 to July 2020
2.Who is most likely to obtain the position of Food Inspector?
A.Roger, who expects to get paid US $ 60,000 a year.
B.Mary, who is a US national and wants a part-time job.
C.Adam, who intends to resign to look for a new job in August 2020.
D.Lucy, who is an American and majored in Food Quality and Safety.
3.Which of the following is TRUE according to the passage?
A.As a Food Inspector, you just need to ensure your food is safe.
B.Department of Agriculture recruits professionals passionate for a PHV career.
C.DoDEA welcomes US citizens and nationals with no prior teaching experience.
D.NAHERC independently researches domestic animal disease outbreaks, threats, or natural disasters.
听下面一段独白，回答以下小题。
1.What is the main idea of this passage?
A.How to decide what to buy in a supermarket.
B.Where to find what to buy in a supermarket.
C.How a supermarket makes people spend more money.
2.Why does the food that everybody must buy spread all over the store?
A.To lead customers to all sections of the store.
B.To make it easy for customers to locate the food.
C.To let customers enjoy the comfortable environment.
3.How much do people spend after they have been in a store for 30 minutes?
A.40 cents each minute.
B.1,500 cents in total.
C.5 dollars each minute.
听下面一段较长对话，回答以下小题。
1.Why did the man make the appointment?
A.His neck has been hurting.
B.He's going on a trip soon.
C.He needs to have his back checked.
2.What may be the time now?
A.11:00 a.m. B.11:30 a.m. C.1:30 p.m.
3.What does the man say about his boss?
A.His boss is a woman.
B.His boss is very understanding.
C.His boss is on holiday.
4.What will the man do after his appointment?
A.Have lunch.
B.Give a presentation.
C.Go to the bank.
