网友您好，请在下方输入框内输入要搜索的题目：

请输入或粘贴题目内容搜题

搜题

拍照、语音搜题，请扫码下载APP

题目内容（请给出正确答案）

[主观题]

When carbon is added to iron in proper ______？

When carbon is added to iron in proper ______the result is steel.

A) rates B ) thicknesses C) proportions D) densities

答案

暂无答案

发布时间：2020-07-03

更多“When carbon is added to iron in proper ______？”相关的问题

第1题

When carbon is added to iron in proper the r？

When carbon is added to iron in proper the result is steel.

A) rates B) densities C) proportions D) thicknesses

点击查看答案

第2题

Spring is usually prime food time for some 1,200 polar bears along Canada's Hudson Bay. Ea

ch year they plunder the bay's ice floes, smash open the snow caves of seals, and stuff themselves on seal pups. But in recent years the bears' feast has turned into slimmer pickings. Why？

Temperatures at Hudson Bay have risen by one half degree Fahrenheit every decade since 1950. Winter ice on the bay melts three weeks earlier than it did just 25 years ago, which means three fewer weeks of polar bear mealtime. Result: Polar bears are 10 percent thinner and produce 10 percent fewer cubs than they did 20 years ago. And though climatologists hotly debate the causes behind Earth's Arctic meltdown, "these changes are startling and unexpected,' says James McCarthy, co-leader of the United Nations Intergovernmental Panel on Climate Change.

The plight of polar bears is just the tip to the iceberg when it comes to mounting evidence of global warming. "There's definitely a stark contrast with the way things were at the start of the 20th century," says atmospheric scientist Leonard Druyan, of Columbia University. Recent data show the volume of Arctic sea ice has shrunk 20 percent since the 1950s; glaciers around the world are melting at rapidly increasing rates. Rivers and lakes in North America, Asia, and Europe now freeze about nine days later and thaw 10 days earlier than they did a century ago.

Most scientists believe the only effective strategy to halt global warming is to drastically reduce emissions of powerful air pollutants like carbon dioxide, which accounts for two-thirds of all greenhouse gases. In the last 150 years, the surging use of fossil fuels coal, oil, and natural gas -- has released 270 billion tons of carbon into the air in the form. of carbon dioxide. Fortunately, oceans, plants, and soils absorb more than half of all atmospheric carbon dioxide -- without them world temperatures might have already soared at an alarming rate.

By saying "Spring is usually prime food time for 1,200 polar bears"？ (Line I, Para. 1), the author means that ______.

A．spring is usually a good time for polar bears to carry out their mating rituals

B．the polar bears usually eat a lot in the spring

C．spring is generally a good time to hunt polar bears

D．polar bears usually hibernate in the spring

点击查看答案

第3题

Global warming is already cutting substantially into potential crop yields in some countri

es—to such an extent that it may be a factor in the food price【C1】______ that have caused worldwide stress in recent years, researchers suggest in a new study. Wheat yields in recent years were down by more than 10 percent in Russia and by a few percentage points【C2】______ in India, France and China compared with【C3】______ they probably would have been without rising【C4】______, according to the study. Corn yields were【C5】______ a few percentage points in China, Brazil and France from what would have been【C6】______, said the researchers, whose findings were published in Fridays【C7】______ of the journal Science. Some countries saw small gains from the temperature increases, however. And in all countries, the【C8】______ carbon dioxide that humans are【C9】______ into the air acted as a【C10】______ that encouraged plant growth,【C11】______ some of the losses from rising temperatures caused by that same greenhouse gas. 【C12】______, the studys authors found that when the gains in some countries were weighed【C13】______ the losses in other countries, the overall global【C14】______ of climate change has been small so far: losses of a few percentage points for wheat and corn from what they would have been【C15】______ climate change. The general impact on production of rice and soybeans was【C16】______, with gains in some regions entirely counterbalancing losses in others. 【C17】______ the authors of the study pointed out that temperature increases were expected to【C18】______ in coming decades, making it likely that the challenges【C19】______ food production will grow in a era when demand is expected to【C20】_____ sharply.

【C1】

A．decreases

B．reductions

C．increases

D．additions

点击查看答案

第4题

根据以下内容，回答下列各题。 Persons who are overweight should watch their diet carefully i

n order to lose pounds. The best way to do this is to start a weight control program. At first it is wise to talk with your doctor. He can advise you of the number of calories(卡路里) you should have in your meals each day. He can tell you about exercisingwhile on your diet. A good rule is to lose slowly. A loss of a pound or two is plenty. Plan meals around foods you know. This means that it is wise to include foods that you are used to and that are part of your regular eating habits. When you have lost the weight you wish, simple items can be added to your diet so that you can maintain the weight you want. While you are dieting, try to build a pattern of eating that you can follow later to maintain your desired weight. When dieting, choose low-calorie foods. Avoid such items as fats. fried food, sweets, cakes, cream and soft drinks. Try to take coffee and tea without sugar or cream. Snacks can be part of your diet. For example, a piece of fruit or a simple dessert saved from mealtime can be eaten between meals. Keep busy ! This way you will not be tempted to go off the diet. Make full use of opportunities to exercise. Try walking instead of riding whenever possible. Happy dieting! What is the main idea of the passage？

A. How to diet.

B. Why we should diet.

C. What we should diet.

D. Where we should diet.

点击查看答案

第5题

When imaginative men turn their eyes towards space and wonder whether life exists in any p

art of it, they may cheer themselves by remembering that life need not resemble closely the life that exists on Earth. Mars looks like the only planet where life like ours could exist, and even this is doubtful. But there may be other kinds of life based on other kinds of chemistry, and they may multiply on Venus or Jupiter. At least we cannot prove at present that they do not.

Even more interesting is the possibility that life on their planets may be in a more advanced stage of evolution. Present-day man is in a peculiar and probably temporary stage. His individual units retain a strong sense of personality. They are, in fact, still capable under favorable circumstances of leading individual lives. But man's societies are already sufficiently developed to have enormously more power and effectiveness

than the individuals have.

It is not likely that this transitional situation will continue very long on the evolutionary time scale. Fifty thousand year's from now man's societies may have become so close-knit that the individuals retain no sense of separate personality. Then little distinction will remain between the organic parts of the multiple organism and the inorganic parts (machines) that have been constructed by it. A million years further on man and his machines may have merged as closely as the muscles of the human body and nerve cells that set them in motion.

The explorers of space should be prepared for some' such situation. If they arrive on a foreign planet that has reached an advanced stage (and this is by no means impossible), they may find it being inhabited by a single large organism composed of many closely cooperating units.

The units may be "secondary"-machines created millions of years ago by a previous form. of life and given the will and ability to survive and reproduce. They may be built entirely of metals and other durable materials. If this is the case, they may be much more tolerant of their environment, multiplying under conditions that would destroy immediately any organism made of carbon compounds and dependent on the familiar car bon cycle.

Such creatures might be relics of a past age, many millions of years ago, when their planet was favorable to the origin of life, or they might be immigrants from a favored planet.

Humans on Earth today are characterized by______.

A．their existence as free and separate beings

B．their capability of living under favorable conditions

C．their great power and effectiveness

D．their strong desire for living in a close-knit society

点击查看答案

第6题

-Bạn ở đâu-Tôi ở（）

A.Văn phòng

B.Khung xe

C.Xe đạp

D.Sợi carbon

点击查看答案

第7题

one carbon unit 名词解释

点击查看答案

第8题

The atmosphere of Mars consists mostly of ______.

A.oxygen

B.carbon dioxde

C.helium

D.nitrous oxide

点击查看答案

第9题

驾驶一直是BMW的强项，iX能够提升驾驶感受的技术有（）

A.Carbon Cage 复合车身结构

B.汉斯，季默打造了专属音乐库

C.第五代电驱技术

D.提供个性、节能、运动三种驾驶风格

点击查看答案

第10题

Earthquakes may rightly be ranked as one of the most destructive forces known to man: si

nce records began to be written down, it has been estimated that earthquake-related fatalities have numbered in the millions, and that earthquake-related destruction has been beyond calculation. The greater part of such damage and loss of life has been due to collapse of buildings and the effects of rockslides, floods, fire, disease, tsunamis (gigantic sea waves), and other observable events resulting from earthquakes, rather than from the quake themselves.

The great majority of all earthquakes occur in two specific geographic areas. One such area covers the Pacific Ocean and its bordering landmasses. The other extends from the East Indians to the Atlas Mountains, including the Himalayas, Iran, Turkey, and the Alpine regions. It is in these two great belts or zones that ninety percent of all earthquakes take place; they may, however, happen anywhere at any time.

This element of the unknown has for centuries added greatly to the dread and horror surrounding earthquakes, but in recent times there have been indications that earthquake forecast may be possible. By analyzing changes in animal behavior, patterns of movements in the earth‟s shell, variations in the earth‟s force of attraction, and the frequency with which minor earth shakes are observed, scientists have shown increasing success in expecting when and where earthquakes will strike. As a result, a worldwide earthquake warning network is already in operation and has helped to prepare for (and thus lessen) the vast destruction that might otherwise have been totally unexpected.

It is doubtful that man will ever be able to control earthquakes and get rid of their destructiveness altogether, but as how and why earthquakes happen become better

understood, man will become more and more able to deal with their possible damage before they occur.

1.Which of the following statements is true according to the passage？

A. Earthquake destruction is declining

B. Earthquake forecast is improving

C. Man is no longer fearful of earthquakes.

D. Man is capable of conquering earthquakes

2.We can infer from the passage that quakes __________.

A. may happen anywhere at any time

B. mostly strike in oceans and mountains

C. are unobservable in masses of land

D. are hardly the direct cause of fatalities

3.The phrase “this element of the unknown” (Paragraph 3) refers to ___________.