1 . 阅读下面短文，在空白处填入1个适当的单词或括号内单词的正确形式。

The summer solstice (夏至) has been widely recognized     1     a festival throughout the world.

The word solstice originates from the Latin sol and sistere,    2     (mean) “sun-standing”. As the days lengthen, the sun rises higher and higher until it seems     3     (stand) still in the sky. It is one of the great turning     4     (point) of the year, when the sun is at its     5     (high) point in the sky during a year.

Today, the day is celebrated around the world. In England thousands gather to welcome the sunrise on the summer solstice. Throughout Europe groups light a fire and stay up all night to welcome the dawn. In Paris, the day     6     (mark) with free concerts during the every year’s Fete de la Musique. When it comes     7     the U.S., the city of Santa Barbara in California holds the country’s biggest celebration     8     lasts a full three-day time. On the East Coast, New York City     9     (traditional) welcomes the summer solstice with a music concert at the Cathedral of Saint John the Divine.

In the southern part of China, Eating lychees (荔枝) druing the summer solstice is a long tradition because eating lychees will cause less “heat” to the body. There is a saying in Shangdong Province that     10     (go), “Eating dumplings on the winter solstice day and eating noodles on the summer solstice day.”

2 . As a popular subject of study among evolutionary ecologists, the three-spined stickleback (三刺鱼) is known for their different shapes, sizes, and behaviors—they can even live in both sea water and fresh water, and under a wide range of temperatures. But what makes that?

The researchers tracked six populations of the fish before and after seasonal changes to their environment, using genome sequencing (基因组测序) . Seasonal changes result in great changes in habitat structure and balance of salt and freshwater, and only those fish able to tolerate these rapid changes survive into the next season.

“These changes probably resemble the habitat shifts experienced by stickleback populations during the past 10,000 years, says Professor Barrett “We hope to gain insight into the genetic changes that may have resulted from natural selection long in the past.”

Remarkably, the researchers discovered the evidence of genetic changes driven by the seasonal shifts in habitats, which mirrored the differences found between long-established freshwater and saltwater populations. “These genetic changes occurred in independent populations over a single season, highlighting just how quickly the effects of natural selection can be detected,” says Professor Barrett, “the findings suggest that we may be able to use the genetic differences to predict how populations may adapt to the environment.”

The research emphasizes the importance of studying species in dynamic environments to gain a better understanding of how natural selection operates. In the further research, they plan to investigate how repeatable the observed genetic changes are, by testing whether they show up year after year. Doing so would demonstrate their ability to reliably forecast the evolutionary future of these populations.

1. What is paragraph 2 mainly about?

A．The difficulties of the research.	B．The purpose of the research.
C．The background of the research.	D．The methods of the research.

2. What is the main reason for the three-spined stickleback’s survival?

A．Habitat shifts.	B．Genetic changes.
C．Seasonal changes.	D．Independent populations.

3. Why will scientists study the repetition of the genetic changes?

A．To know what natural selection is.

B．To study species in dynamic environments.

C．To test the reliability of the present discoveries.

D．To forecast the evolutionary future of certain species.

4. Where is the text from?

A．A science magazine.	B．A science fiction.
C．An advertisement.	D．A novel.

3 . Which season is it now?

A．Spring.

B．Summer.

C．Winter.