Why Dogs Chase Their Tails
It might look like a strange activity to humans, but tail-chasing is a way for dogs to burn off some energy. In most cases, they're doing this for one of two reasons:
If a dog doesn’t have anything (or anyone) to play with, it might need to entertain itself—in this case, by playing with its tail. On the other hand, the behavior could be a warning sign that your dog is becoming anxious or stressed. ''We call these displacement(替代) behaviors, similar to a human playing with their hair or tapping their foot, '' says Hartstein. ''
One reason tail-chasing can be a must-do for dogs is that they start playing with their tails as playful puppies learning about their bodies.
| A．They are happy and content |
| B．They're bored or they're stressed |
| C．A visit to the vet is also a good idea |
| D．They gradually get into the habit of chasing tails |
| E．Owners often laugh at the activity and talk about it |
| F．They seek to do things that can comfort themselves |
| G．It’s normal for dogs to chase their own tails every now and then |
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【推荐1】The latest data from Nature's Calendar shows that the butterflies, newts and nest-building blackbirds have been spotted months before they would normally appear. An analysis of the conditions in 2019 found that all but one of the 50 spring events the scheme (计划)tracks were early last year, as a result of warmer winter temperatures. The Woodland Trust, which runs the Nature's Calendar scheme, warns that many species are losing their seasonal cues (提示)as winters warm and seasons shift.
Increasingly unstable weather could tempt some animals out of hibernation (冬眠)too soon, only to be hit by sharply dropping temperatures. And some birds appeared to be breeding too late to make the most of vital food sources that appear earlier than normal, the Trust said.
Lorienne Whittle, at the Woodland Trust, said, “It seems that last year we almost lost winter as a season — it was much milder and our data shows wildlife is responding, potentially putting many at risk.”
And she said, “It appears that some species are able to adapt to the advancing spring better than others. Oak trees respond by producing their first leaves earlier and caterpillars seem to be keeping pace. But blue tits, great tits and pied flycatchers are struggling to react in time for their chicks to take advantage of the peak amount of caterpillars— the food source on which they depend.”
Active newts were recorded in late December in Cheshire and a blackbird was spotted building a nest at the beginning of January. Accordingly, a report for The Wildlife Trust suggested that hedgerows (树篱)be protected from being cut during the nesting season.
1. What does the underlined word “tempt” in paragraph 2 probably mean?| A．help. | B．attract. | C．guide. | D．threaten. |
| A．To explain why plants respond to the climate change. |
| B．To prove some species fit in with the climate change better. |
| C．To show how caterpillars react to the changing environment. |
| D．To suggest plants adapt to warmer winters better than animals. |
| A．By listing environmental damages. | B．By offering practical suggestions. |
| C．By making striking comparisons. | D．By presenting tracking results. |
| A．Warmer winters: Wildlife under threat | B．A practical scheme: Protection under way |
| C．A big danger: Birds' dying out | D．A hard journey: Plants' struggling to survive |
【推荐2】In 2018, Russian scientists took a soil sample from deep in the permanently frozen ground in Siberia in Russia. They discovered two tiny round nematodes (线虫) frozen in the sample, which were so small that they could only be seen with a microscope. Tests showed the soil had been frozen for about 46,000 years old. When the nematodes were placed in room temperature, they began to move. The nematodes are the oldest living animals ever brought back to life after being frozen. The discovery makes up for the research on how living things can survive in tough conditions.
Nematodes can live for years if they’re frozen. They can enter a special state called cryptobiosis (隐生现象) , during which animals reduce their activities and consume very little energy. Before this, the longest nematode had been known to survive through cryptobiosis was about 25 years. Being revived after 46,000 years was a new record for any kind of animal.
The nematodes were sent off to Germany to be studied further. The researchers found the two nematodes were a new species of nematode that had not yet been discovered. That’s not too surprising, since there are so many species of nematodes. They also found the nematodes were able to survive being frozen better if they were dried out a little first. The drying helped them produce a special sugar called trehalose (海藻糖), which helped them survive being frozen. The scientists also studied a nematode species that is common these days. They found that it also uses the sugar to protect itself in cryptobiosis.
Both of the nematodes were females. Before long, they began to have babies. Some kinds of nematodes, including these, have the ability for a single nematode to have babies all by itself. The two original frozen nematodes have now died. But their babies had babies who had babies, and so on. Most of the nematodes only live a month or two unless they get frozen.
1. What do we know about the two nematodes in the first paragraph?| A．They were the oldest living animals. |
| B．They were still alive when warmed up. |
| C．They were found on the surface of the ground. |
| D．They were the tiniest creatures ever discovered. |
| A．It slows down the pace of their life. |
| B．It helps them speed up their drying. |
| C．It gets their body temperature down. |
| D．It stops them from consuming energy. |
| A．Cryptobiosis. | B．Trehalose. | C．Their sex. | D．Dry condition. |
| A．Female nematodes live longer than the male ones |
| B．Nematodes can produce young when they are frozen |
| C．Nematodes are ranked the fastest producing creatures |
| D．Short-lived nematodes survived for thousands of years |
【推荐3】There is little doubt that house cats first developed naturally from ancient wild cats. The closest relative is the African wild cat which still lives in Africa today. This is understandable because the first house cats came from Africa.
Cats first started to live around people in Egypt about 6,000—7,000 years ago. From Egypt, cats started to move around the world. This is about the same time that Egyptians began storing grain in buildings. Scientists used to believe that people tamed cats to catch mice and protect the grain. However, cats don’t like to be told what to do! Now, scientists believe that cats followed the mice and learned to accept people. Finally, some of the cats began to grow comfortable around people. These were smaller cats that needed protection. As these cats and people got used to each other, then they moved in together. Around 5,000 years ago, cats started to live with people.
Soon cats were in Greece, then the Middle East and China. They moved along Egyptian business roads keeping away mice and keeping people around them. After the Romans came to Egypt, they also accepted the cats and brought them to Europe. These cats likely bred with other cats to form the many kinds of house cats we have today.
Cats are relatively recent house animals. House cats still have a lot in common with their wild relatives. Cats sleep a lot to save energy just like wild cats. They will often get food at night as well. House cats are generally peaceful and friendly, but be careful! If a cat feels it is in danger, it will fight back—just like a wild cat!
1. Where did the first house cats come from?| A．Asia. | B．Africa. | C．Europe. | D．America. |
| A．About 4,000 years ago. | B．About 5,000 years ago. |
| C．About 6,000 years ago. | D．About 7,000 years ago. |
| A．Cats started to move around the world from China. |
| B．Cats get food at night to save energy like wild cats. |
| C．Cats have a little in common with their wild relatives. |
| D．Cats were accepted and brought to Europe by Romans. |
| A．The development of house cats. | B．Different cats in different countries. |
| C．The relationship between cats and people. | D．The differences between house cats and wild cats. |
