题目内容
A rainbow is a natural （现象）.
阅读快车系列答案In Asia, there are special competitions where kites have complex designs and are fitted with instruments that make musical sounds as the wind blows through them. Although all kites have a similar structure （结构）, they are widely different in size and shape. Kite-fighting competitions are also held, in which competitions us their kites to attack and bring down their opponents’（对手）kites or cut their strings（线）.
For more than 15 years, the Big Wind Kite Factory has been giving kite-making and kite flying classes for the children on an island in Hawaii. In its kite-making lessons, students can make kites in as little as 20 minutes! Children as young as four years old can learn how to fly a kite. Jonathan Socher and his wife Daphne started the kite factory in 1980. Their kites are made of nylon（尼龙）.Their designs are Hawaiian themes created by Daphne. The designs are cut out of the nylon with a hot knife that seals the edges and then fastened directly onto the kite.
The kite that is used to give lessons is regular diamond kite with a rainbow pattern. The difference between this kite and the ones they make during the lessons is that it is a two-string controllable kite. Big Wind employees fly the kite and for a few minutes show students how pulling on one line and then on the other controls the direction the kite goes in. Then the controls are given to the students.
Jonathan insists that it is not necessary to make a huge impressive kite to have fun making and flying kites. Even the simplest structure can work, and can give hours of fun. Go on, give it a try!
【小题1】Which of the following is true according to the text?
| A．A hot knife is used to iron the nylon. |
| B．Children never fly kites on their own in flying lessons. |
| C．Kite strings must not be cut in kite-fighting competitions. |
| D．Daphne designs kites for the Big Wind Kite Factory. |
| A．It has two strings. |
| B．It is simple in design |
| C．It has a rainbow pattern. |
| D．It is shaped like a diamond. |
| A．A large kite. |
| B．Any type of kite. |
| C．A complex structure. |
| D．A kite that impresses others. |
| A．A kite factory |
| B．Kite-flying lessons. |
| C．Special competitions. |
| D．The kite-making Process. |
Have you ever wondered why there are so many skin colors in the world? Do you know why people living in particular areas usually have a certain color? Biology and history are the two reasons for this.
Skin contains something called melanin, which determines a person’s skin color. The more melanin a person has, the darker his or her skin will be. The amount of and the production of melanin are controlled by genetics, but can be affected by other things, such as sunlight. If a person lives in a place with less sunlight, a person’s body will produce less melanin, making the skin lighter.
Skin color is also affected by another source ---- vitamin D. humans all need vitamin D to build bones. People can get it by eating foods such as fish and milk, or from sunlight, so sunlight absorbed by melanin cannot be used for vitamin D production. Therefore, a dark—skinned person will produce less vitamin D than a light—skinned person when they received the same amount of sunlight.
The connection between vitamin D production and skin color is clear when we look at evolution. The earliest humans lived in Africa, their dark skin produced less vitamin D because of their dark skin. As a result, their skin made less melanin, so they could get enough sunlight to produce vitamin D. their skin gradually got lighter and they lost hair. Now, people living in areas with strong sunlight like Africa, have darker skin, while people living in other areas have lighter skin. The exception to this is the Inuit, who live in a place with little sunlight, but have dark skin because they eat a lot of fish and have enough vitamin D.
Evolution has given us a rainbow of skin colors. Humans have always had melanin to determine our skin color. What has changed through history is the environment where we have lived. This has in turn changed our melanin production, and eventually, skin color.
| Brief 1 | People living in a particular 2 usually have the same skin color and there are many different skin colors in the world. |
| Reason for skin color | The reasons for different skin colors mainly 3 in biology and history. |
| Biology reasons | The amount of melanin, by which a person’s skin color is __4 , varies from people to people. The more melanin a person has, the __5 his or her skin will be. Vitamin D is another source 6 skin color. Vitamin D is necessary for humans to build bones. Sunlight contributes to vitamin D in the skin. |
| Historical reasons | The earliest people in Africa hioknj006Dad dark skin with hair covering it because the sunlight is very strong. When they moved to places where they could not get enough sunlight to __7___ vitamin D, their skin color became lighter. Generally speaking, people in areas with strong sunlight, have darker skin ____8 people in other areas have lighter skin. |
| 9 | Melanin 10 an important role in our skin color. With our living environment changing, melanin production is changed, which leads to the changes in our skin color. |