题目内容
（请给出正确答案）
Earth has an atmosphere, which protects the surface from harmful rays.
A．minerals
B．substances
C．gases
D．beams
如果结果不匹配，请 联系老师 获取答案
更多“Earth has an atmosphere, which…”相关的问题
A.Chinese zodiac is based on time periods of birth
B.Western constellation has 12 symbols or signs with associated personalities and fortunes
C.Western astrology are based on constellations' positions relative to the earth
D.Western astrology is calculated on ayear-by-yearbase
Which of the following is true of Livingston？
A．He thinks he has discovered a new possibility in the link between sun spots and the weather on the Earth.
B．He has great doubts about the theory that the sun' s frequent changes have an influenced on the Earth' s climate.
C．He has been recently informed by other scientists of the possibility that more sun spots will appear.
D．He does not think the causes of the sun spots will be fully revealed by scientists in the near future.
The sun is one of the stars.Some planets are balls of rock and some are balls of gas.We live on the planet earth.The earth spins around once every day to give us day and night.The earth goes around the sun once every year to give us different seasons.
There are eight planets moving around the sun.We call the family of the sun and its planets the solar system.Mercury is the nearest to the sun, so it is very hot.It is the smallest planet.Venus is very bright and hot.It is the nearest to the earth.Mars is covered with orange-red desi and rocks, so it looks like a red star in the sky.It has seasons like the earth.Jupiter has more than 16 moons (卫星)and it is the biggest and heaviest planet.Saturn has more than 22 moons.The other planets, such as Uranus and Neptune, are all very far from the sun and very cold.We need a telescope (望远镜) to see them.
(1)The sun can give us().
A.heat and water
B.heat and light
C.light and air
D.rock and water
(2)The Chinese meaning of "spin around" is().
A.飞行
B.行驶
C.环绕
D.旋转
(3)The earth goes around()once every year to give us different seasons.
A.the moon
B.Mars
C.Jupiter
D.the sun
(4)Mars looks red in the sky because().
A.it is covered with orange- red dust and rocks
B.it has seasons like the earth
C.it is the nearest to the earth
D.it is covered with red water and dust
(5)Which is NOT true according to the passage？ ()
A.Jupiter is the biggest and heaviest planet.
B.Uranus is very far from the sun and very cold.
C.The revolution(公转) of the earth gives us different seasons.
D.We call the family of the sun and its planets the Milky Way.
A.a natural course which is to some degree helpful to us
B.the way．in which gases are used for keeping plants warm
C.the way“greenhouse gases”trap heat on the earth
D.the whole course in which greenhouse gases prevent heat
During the past 200 years the world population has increased 6 times, the annual world output has increased 80 times, and the distance a person can travel has gone up 1,000 times. There has also been much recent progress in art, culture, learning, and science. Such changes have led to a high rate of production and growth of the economy.
Economists fear that within the next 100 to 150 years, the earth's resources will become very scarce. Their fears are partly justified, but we should not be afraid. Industrial civilization adapts to new knowledge. By advancing knowledge, we not only create new forms of resources, but we also find ways to economize their use. Advanced modern knowledge can feed the hungry people of the world and improve their standard of living.
The figures in the second paragraph are used for the following purposes EXCEPT______.
A．prediction.
B．contrast.
C．definition.
D．explanation.
Today, Americans are still fond of trying their hand at becoming small business people, even though only one out of two survives the first two years. Many of these people start their businesses for the wrong reasons: to get away from the paper work of their present jobs or to exchange the responsibility of their present jobs for freer life styles. But more, not less, paper work and responsibility come with ownership of a small business. John Shuttleworth, owner of the recently successful life-ecology news magazine Mother Earth, reports having had to work sixty hours straight in order to bring out the first issue.
John Shuttleworth waited years after conceiving the idea for Mother Earth before he attempted to put out the first issue. During that time, he collected as much information as he could about his proposed venture. He borrowed books about business from the library; he talked to people already established in the field; and he began planning in detail the amount of money and the kinds and numbers of supplies he would need. When he finally opened with a capital of $1,500, he set up his office in the kitchen of his home and his printing press in the garage. Due to his devotion to business his managerial skill, and his talent, Mother Earth now has a circulation of 300,000:
Not all small business succeed as well as Mother Earth has. Fifty percent of the 450,000 that start in the United States every year fail. Still, ninety-five percent businesses in the States can be described as small. Combined, these businesses account for forty percent of America's gross national product.
According to this passage, many people start their own businesses for the wrong reasons. The reasons are wrong because they do not realize that ______.
A．their own businesses will provide large income but less responsibility
B．their own businesses will not relieve them from paper work and responsibility
C．their own businesses will require longer working hours but less paper work
D．their own businesses could easily fail
Radiocarbon Dating
Nowadays scientists can answer many questions about the past through a technique called radiocarbon(放射性碳), or carbon-14, dating. One key to understanding how and why something happened is to discover when it happened.
Radiocarbon dating was developed in the late 1940s by physicist Willard F. Libby at the University of Chicago. An atom of ordinary carbon, called carbon-12, has six protons(质子) and six neutrons(中子) in its nucleus. Carbon-14, or C-14, is a radioactive, unstable form. of carbon that has two extra neutrons(原子核). It returns to a more stable form. of carbon through a process called decay(衰减). This process involves the loss of the extra neutrons and energy from the nucleus.
In Libby's radiocarbon dating technique, the weak radioactive emissions(放射) from this decay process are counted by instruments such as a radiation detector and counter. The decay rate is used to determine the proportion of C-14 atoms in the sample being dated.
Carbon-14 is produced in the Earth's atmosphere when nitrogen(氮)-14, or N-14, interacts with cosmic rays(宇宙射线). Scientists believe since the Earth was formed, the amount of nitrogen in the atmosphere has remained constant. Consequently, C-14 formation is thought to occur at a constant rate. Now ratio of C-14 to other carbon atoms in the atmosphere is known. Most scientists agree that this ratio is useful for dating items back to at least 50,000 years.
All life on Earth is made of organic molecules(分子) that contain carbon atoms coming from the atmosphere. So all living things have about the same ratio of C-14 atoms to other carbon atoms in their tissues(组织). Once an organism(有机体) dies it stops taking in carbon in any form, and the C-14 already present begins to decay. Over time the amount of C-14 in the material decreases, and the ratio of C-14 to other carbon atoms goes down. In terms of radiocarbon dating, the fewer C-14 atoms in a sample, the older that sample is.
Nowadays many scientists depend on radiocarbon for dating age-old objects.
A．Right
B．Wrong
C．Not mentioned
Italian astronaut Samantha Cristoforetti talks about daily life on the international Space Station(ISS).
For the last few months, my home has been the International Space Station, orbiting 400 km above the surface of the earth, at 25, 000 km per hour. We took off in a Russian Soyuz spaceship from Kazakhstan, and the flight to the Space Station took six hours. (1) I felt incredibly excited.
There are two Americans, three Russians, and me. (2) Fortunately, we all get on well. The day starts for everyone at 7 a.m. There's no gravity up here, so, every morning I float through the cabin to attend our daily planning conference, or DPC. (3) It usually lasts a few minutes. After it's finished. we speak to space centres around the world, including Houston (USA), Munich (Germany) and Tsukuba (Japan).
Then we have breakfast: oatmeal, eggs and coffee. In the past, astronauts had to suck food out of tubes. Nowadays, astronauts' food is served in special individual boxes with covers. (4) Life has become much easier for astronauts over the years.
Our dinner is at around 7.30 p.m. My meals were prepared by an Italian chef on Earth before left, and they're delicious. However, I do exchange a lot of food with my three colleagues from Russia.
(5) Their lentil and vegetable soup is also really good. Of course, I miss fresh food, but a cargo spaceship comes once a month with fresh fruit. When I get back down to Earth, I know I'll miss this peace.
A.I'm the only woman in this group.
B.That was a very long time to live in space.
C.People often ask what food tastes like in space.
D.This stops everything floating away while we eat!
E.On the other hand, the ISS is a perfect environment to do scientific experiments.
F.That's the meeting where we discuss what needs to be done during the day.
G.They like my desserts, and they have a dark bread that I love.
H.I'll never forget looking through the window and seeing it for the first time.
The source of the sun' s inconstancy is magnetism. Professor William Livingston has developed new theories about its magnetic nature.
"We don' t yet know what causes sun spots, "he says, "but we now think they ' re areas of high level magnetism that come up from the sun' s interior. So strong is their magnetic pull that the highly ionized gas nearby is not able to transmit energy out. "As a result these areas send out less heat and light and thus appear from Earth to be almost dark irregular surface patches.
Sun spot activity generally fluctuates in steady, 11-year cycled. Scientists have long formed the o pinion that as the size and number of sun spots increased, the overall energy sent out by the sun would de crease. Indeed, recent studies confirmed it, revealing that during peak periods of sun spot activity, the Earth experiences a small drop that can be seen clearly in received solar energy.
Could such a small drop in energy have an effect here on earth？ Perhaps some scientists think the world temperature could fall by' as much as 0.2 during periods of high solar magnetism.., enough to cause significant fluctuations in weather patterns.
According to the passage, it is believed that the sun ______ ．
A．moves in a quick but steady way year after year
B．sends out less and less heat and light with each passing year
C．radiates the same amount of light every year
D．might have a strong influence on the weather patterns
