【推荐1】What Are Grasslands?

Grasslands are wide areas of land covered with low growing plants such as grasses and wildflowers. Grasslands don’t get enough rain to grow tall trees and produce forests, but they get too much rain to form a desert. Temperate (温带的) grasslands have different seasons including hot summers and cold winters.

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Grasslands are generally found between deserts and forests. The major temperate grasslands are located in central North America in the United States, in southeast South America in Uruguay and Argentina, and in Asia along the southern part of Russia and Mongolia.

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A variety of animals live in the grasslands, including dogs, wolves, and eagles. A lot of smaller animals hide down in the grass, such as snakes, mice, and rabbits.

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Different kinds of grass grow in different areas of the grasslands. There are actually thousands of different kinds of grass that grow in this type of environment. Where they grow usually depends on the amount of rain that area gets. In wetter grasslands, there are tall grasses that can grow up to six feet high. In dryer areas the grasses grow shorter, maybe only a foot or two tall. Other plants that grow there include sunflowers, butterfly weeds, and butterweeds.

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Grasslands play an important role in human farming and food production. They are used to grow crops such as wheat and corn. They are also good for feeding farm animals such as cows.

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Unfortunately, human farming and development has caused the grasslands to become gradually smaller. Governments have carried protection measures to try and save the grasslands that are left, along with the endangered plants and animals that live there.

A．The Narrowing Grasslands

B．Animals in the Grasslands

C．Some Important Temperate Grasslands in the World

D．Farming and Food

E．Wildfires in the Grasslands

F．Types of Temperate Grasslands

G．Plants in the Grasslands

【推荐2】In recent studies we have been investigating mirror writing by typical 4- to 6-year-old children. The term is used because the characters — numbers and capital letters — are reversed (反向), yet are correct when looked at in a mirror.

Mirror writing entered the scientific literature in 1878. The explanations for the phenomenon were not only insufficient but also often wrong. One of them is — writing with the left hand. Throughout the 20th century, scientific journals have published mirror writing mostly produced by left-handed children. Even today, left-handedness is often the favorite explanation of teachers when children produce mirror writing.

The explanation we find for the phenomenon of mirror writing of characters works on two successive levels, the first cerebral and the second behavioral. The cerebral level shows that the brain removes orientation (left or right) when storing images, a process called symmetrisation or mirror generalization. This mirror-generalization process leads children aged 5 to know, from memory, the shape of the characters, but not their left/right orientation. Given the features of the process — horizontal mirror in the visual modality (视觉模式) — it is important to note that the initial learning of the form of the characters by the children is mainly visual, and that the children only produce horizontal mirror writing.

At the behavioral level, when children write the characters from memory, they must give them an orientation. In countries whose primary languages are written in Latin characters — written from left to right — children most often point them toward the right. This leads them to reverse mainly the left-oriented characters: J, Z, 1, 2, 3, 7, and 9. However, when spatial constraints cause them to write from right to left, the children instead reverse the right-oriented letters.

Since this explanation has nothing to do with the handedness of the children, it can be predicted that right-handed children will reverse characters almost often as left-handed children, and that – left-handed or right-handed – children will primarily reverse left-oriented characters in Western culture. This is because they strictly orient the characters in the direction of writing.

1. What aspect of a character does mirror generalization help children to know?

A．Its form.	B．Its pronunciation.
C．Its meaning.	D．Its orientation.

2. Which paragraph shows why mirror writing is reversed horizontally rather than vertically (垂直)?

A．Paragraph 2.	B．Paragraph 3.
C．Paragraph 4.	D．Paragraph 5.

3. Which of the following is likely to be reversed by a child writing from right to left?

A．M.

B．C.

C．8.

D．9.

4. What can we learn from the study?

A．Handedness is the main reason for mirror writing.

B．Right-handed children won’t write reversed characters.

C．Left-handed children reverse right-oriented characters more often.

D．Children in the US tend to primarily reverse left-oriented characters.

【推荐3】A team of machine learning developers has created a system for making caricatures (人物漫画) of people’s faces.

In a caricature, the artist creates a drawing of a face, with different parts of it greatly enlarged or exaggerated (夸大). The pictures or images are usually made to make the person look funny.Such drawings can be difficult for machines to produce. This is because the human face is made up of complex shapes with a lot of extremely small details. Generally, good caricatures require skilled artists who can effectively exaggerate faces, while still staying true to life.

Kaidi Cao, leading the research, said that other machine systems for creating caricatures depended on a series of rules, which were based on how people would draw. However, his team’s system used machine learning to create the caricatures from thousands of examples made by experienced artists. In addition, the system gave users more ability to change results in both shape and appearance exaggerations.

The team tested how recognizable its caricatures were to human test subjects. People were shown caricatures and then asked to choose the correct one from a group of images with faces that looked very similar. Test results showed that in many cases, people had difficulty choosing the correct images when the caricatures were created with the older methods. The researchers said that it was because such systems often created caricatures that were far too exaggerated or unclear. Not surprisingly, the most easily recognized caricatures in the experiment were made by humans. But the researchers said that their system performed better in tests with human subjects than the older methods. 

To date, the team has mostly worked on developing caricatures of people’s faces, but they plan to expand on this in the future to include full bodies and other objects. They also plan to explore turning the current model around to permit caricature-to-photo translation. The team said that they believed this might be useful for facial recognition of caricatures.

1. Why is it hard for machines to draw a caricature of a person’s face?

A．It offers too few examples.	B．It has too many different expressions.
C．It has various shapes with small details.	D．It fails to attract the machines' attention.

2. What is the advantage of Kaidi Cao’s system?

A．It knows clearly how people draw.	B．It strictly observes a series of rules.
C．It’s controlled by experienced artists.	D．It enables users to change their works.

3. What will Kaidi Cao’s team do in the future?

A．Create more caricatures of people’s faces.

B．Make their caricatures easy to recognize.

C．Develop more systems for making caricatures.

D．Make their system translate caricatures into pictures.

4. What does the text mainly talk about?

A．Ways to create caricatures of people’s faces.

B．New machine systems for making caricature faces.

C．A research on how people would draw caricatures.

D．A team of machine learning developers’ new plans.