Although extinction and impact events are natural phenomena, we must find a way to prevent

When these early migrants arrived in North America, they found the woods and plains dominated by three types of American mammoths. These elephants were distinguished from today's elephants mainly by their thick, shaggy coats and their huge, upward-curving tusks. They had arrived on the continent hundreds of thousands of years before their human followers. The wooly mammoth in the North, the Columbian mammoth in middle North America, and the imperial mammoth of the South, together with their distant cousins the mastodons, dominated the land. Here, as in the Old World, there is evidence that humans hunted these elephants, as shown by the numerous spear points found with mammoth remains.

Then, at the end of the Ice Age, when the last glaciers had retreated, there was a relatively sudden and widespread extinction of elephants. In the New World, both mammoths and mastodons disappeared. In the Old World, only Indian and African elephants survived.

Why did the huge, seemingly successful mammoths disappear？ Were humans connected with their extinction.* Perhaps, but at that time, although they were cunning hunters, humans were still widely scattered and not very numerous. It is difficult to see how they could have prevailed over the mammoth to such an extent.

Which of the following conclusions about mammoths does the passage support？

A．Humans hunted them to extinction.

B．The freezing temperatures of the Ice Age destroyed their food supply.

C．The cause of their extinction is not definitely known.

D．Competition with mastodons caused them to become extinct.

Questions 6 to 10 are based on the following passage:

Half of the world&39;s coral reefs （珊瑚礁）have died in the last 30 years. Now scientists are racing to ensure that the rest survive. Even if global warning were to right now, scientists predict that more than 90% of corals will die by If no major steps are taken to address the problem, the reefs may be headed for total extinction （灭绝）.

(78) The planet ’s health depends on the survival of coral reefs. They described as “the rainforests of the sea", because they provide shelter for a wide variety of sea life. In addition, the reefs serve as barriers that protect coastlines from the full force of powerful storms. Coral are used in medical research for cures to diseases. They are key to local economies as well, since the reefs attract tourists, the fishing industry, and other businesses, bringing in billions of dolllars.

（79）Corals are particular sensitive to changes in temperature. A rise of just 1 to 2 degrees can force the corals to drive out the algae （水藻）. Then the corals turn white in a process called “bleaching”. Corals can recover from short-term bleaching, but long-term bleaching can cause permanent damage. In 1998, when sea surface temperatures were the highest in recorded history, coral reefs around the world suffered the most severe bleaching. It is estimated that even under the best of conditions, many of these coral reefs will need decades to recover.

Although reefs face other threats from pollution, industrial activities, and overfishing, it is global climate change that most concerns scientists. Scientists remain hopeful that it’s not too late to save the reefs, and some are moving ahead on experiments to accomplish that goal.

6. Which of the following is the best title for the passage？

A.Rising Global Temperatures

B.Rainforests Are in Danger

C.Coral Reefs Face Extinction

D.Global Climate Change

The word address in Paragraph 1 is closest in meaning to _____.A.break down

B.stick to

C.go over

D.deal with

Why are coral reefs called "the rainforests of the sea"？A.Because they are home to a wide variety of sea life.

B.Because they can protect our coasts from storms.

C.Because they might supply natural medicines.

D.Because they look like rainforests.

According to the passage, _____ is the biggest threat to coral reefs.A.pollution

B.overfishing

C.industrial activity

D.dimate change

The corals turn _____ in the process of “bleaching”.A.red

B.black

C.green

D.white

Questions 6 to 10 are based on the following passage:

Half of the world&39;s coral reefs （珊瑚礁）have died in the last 30 years. Now scientists are racing to ensure that the rest survive. Even if global warning were to right now, scientists predict that more than 90% of corals will die by If no major steps are taken to address the problem, the reefs may be headed for total extinction （灭绝）.

(78) The planet ’s health depends on the survival of coral reefs. They described as “the rainforests of the sea", because they provide shelter for a wide variety of sea life. In addition, the reefs serve as barriers that protect coastlines from the full force of powerful storms. Coral are used in medical research for cures to diseases. They are key to local economies as well, since the reefs attract tourists, the fishing industry, and other businesses, bringing in billions of dolllars.

（79）Corals are particular sensitive to changes in temperature. A rise of just 1 to 2 degrees can force the corals to drive out the algae （水藻）. Then the corals turn white in a process called “bleaching”. Corals can recover from short-term bleaching, but long-term bleaching can cause permanent damage. In 1998, when sea surface temperatures were the highest in recorded history, coral reefs around the world suffered the most severe bleaching. It is estimated that even under the best of conditions, many of these coral reefs will need decades to recover.

Although reefs face other threats from pollution, industrial activities, and overfishing, it is global climate change that most concerns scientists. Scientists remain hopeful that it’s not too late to save the reefs, and some are moving ahead on experiments to accomplish that goal.

6. Which of the following is the best title for the passage？

A.Rising Global Temperatures

B.Rainforests Are in Danger

C.Coral Reefs Face Extinction

D.Global Climate Change

The word address in Paragraph 1 is closest in meaning to _____.A.break down

B.stick to

C.go over

D.deal with

Why are coral reefs called "the rainforests of the sea"？A.Because they are home to a wide variety of sea life.

B.Because they can protect our coasts from storms.

C.Because they might supply natural medicines.

D.Because they look like rainforests.

According to the passage, _____ is the biggest threat to coral reefs.A.pollution

B.overfishing

C.industrial activity

D.dimate change

The corals turn _____ in the process of “bleaching”.A.red

B.black

C.green

D.white

请帮忙给出每个问题的正确答案和分析，谢谢！

Mammals have a number of features that distinguish them from the reptiles from which they developed. They are warm blooded; that is, they have a system of temperature control that keeps the body at a constant temperature. Mammals have a set of teeth of different shapes that serve different functions such as cutting, gouging, and grinding. Young mammals spend their earliest days of development shielded within the mother's body and are then born alive, rather than hatching from eggs. In addition, after birth they are nourished by milk provided by the mother's mammary glands. The enforced association between mother and infant provides an opportunity for learning that does not exist for those kinds of creatures that are hatched from eggs long after their parents have departed from the scene. Young mammals play -- something that amphibians and reptiles never do -- which provides additional learning opportunities.

The foregoing list leaves little doubt that we are mammals. There are, of course, a great many kinds of mammals, most of which developed after the great extinction of dinosaurs and other reptiles about 65 million years ago that opened opportunities for the few small mammals that were already in existence. One of the groups of mammals that resulted was a biological order called Primates which includes monkeys, apes, humans, and some smaller creatures familiar only to ardent zoogoers. Primates share a number of behavioral features that have played important roles in their evolutionary development. Most primates are arboreal; that is, they spend their lives in and among trees. Their tree-climbing and tree-dwelling habits impose needs that are reflected in primate anatomy. Although diet varies from species to species, many primates are largely vegetarian. But they can eat and digest meat, and some species vary their diets of leaves, shoots, and fruits by eating insects, birds' eggs, and even small animals. Primates are hand-feeders, depending on their hands both to collect food and to get it into their mouths. Perhaps the most important feature of their behavior. is that primates are social animals. Their genetics, habits, and even their survival are geared to living in groups. Although human beings have come to have a way of life very different from that of typical primates, the basic primate adaptation provided prehumans with capabilities that allowed them to become culture？ builders.

The anatomical features that separate primates from other kinds of animals relate clearly to the way primates behave.

Where do you think is the passage from？

A．Newspaper.

B．Gazette.

C．Journal.

D．Science magazine.

A.消费

B.灭绝

C.文化

A.物质

B.存在

C.灭亡

A.本能

B.灭绝

C.阻碍

D.保护

A.灭绝

B.减少

C.增加

D.失败

A.出境

B.出口

C.灭绝