1 . Worldwide, there are more than a thousand mistletoe (槲寄生) species. They grow on every continent except Antarctica. They are parasites(寄生物) and live on the branches of their plant “hosts”, absorbing water and nutrients to survive. They accomplish this thievery via a specialized structure that infects their hosts. In fact, they infect plants of all kinds, including themselves—a number of species have been documented parasitizing other mistletoe species.

Yet despite their parasitism, mistletoe species may well be the Robin Hoods of plants.(Robin Hood is a character in old English stories who lives in a forest with a group of friends and steals money from rich people in order to give it to poor people.) They provide food, shelter and hunting grounds for other animals. Fallen mistletoe leaves release nutrients into the forest floor that would otherwise remain locked within trees, and this generosity benefits the food chain. “Yes, ecologically, they are cheats,” says David Watson, a community ecologist at   Charles Sturt University at Albury-Wodonga, Australia. But they share their wealth. “They steal these nutrients, and then they drop them,”   Watson says.

Mistletoe species depend critically on animals to get around. Most mistletoe fruits are berries containing a single seed that’s surrounded by a sticky layer. Roughly 90 bird species are known to consume mistletoe species’ seeds, so the birds can pass them to other trees on their bodies, or when they are eaten, seeds are passed through their waste. (There are exceptions:   Some mistletoe species make explosive fruits that send their seeds toward nearby trees,   reaching distances of 10 meters or more.)

Scientists have known that mistletoe species all have ancestors that were parasites not on branches, but on roots.   “They evolved over and over and over, and this understory,   root-parasitic, shrubby thing switched to being an aerial(meaning they infect above-ground plant parts, rather than roots), parasitic shrubby thing,” Watson says. Moving up the tree helped to solve a problem that all plants are faced with: competing for sunlight. Despite their parasitic nature, most mistletoe species still use energy from light to make their food.

1. What can we learn about mistletoe species according to paragraph 1?

A．They are highly independent.	B．They are harmful to their hosts.
C．They can be found on every continent.	D．They prefer to live on the roots of plants.

2. In what way are mistletoe species similar to Robin Hood?

A．They help poorly grown trees absorb more nutrients.

B．They have remarkable abilities to survive in the forest.

C．They live in the forest with other plant species in groups.

D．They steal and give food to many other living things.

3. How do most mistletoe species spread their seeds?

A．With the help of birds.	B．By making explosive fruits.
C．With the help of nearby trees.	D．By taking advantage of hosts’ seeds.

4. What does Watson tell us about the evolutionary development of mistletoe species?

A．They eventually evolved into shrubby plants.

B．Their habitats changed from roots to branches.

C．They tried to give up using energy from sunlight.

D．Their parasitic nature was formed in a gradual way.

2 . After tracking flowers on a prairie (草原) in Minnesota for 21 years, scientists reported that the plants reproduce more successfully in the year following a carefully controlled burn. Understanding the relationship between prairie plants and fire is important for preserving this ecosystem which is becoming rapidly smaller, says Stuart Wagenius, a conservation scientist.

Fire provides an additional advantage for the narrow-leaved purple coneflower (紫锥花), as Wagenius and his colleagues say. To really bloom (开花), they need a little help: Enter the fire. Between 1996 and 2016, Wagenius says his team tracked nearly 8,000 purple coneflowers on the Staffanson Prairie Preserve. In 9 of those years, they conducted controlled burns over 400 times. “In the summer after a burn, many more plants flower,” Wagenius says. “It is just a huge flowering festival.”

Purple coneflowers and many other prairie plants were previously known to bloom energetically after fires. However, the researchers said that fire also stimulated purple coneflowers to bloom at the same time in the summer after a burn. This meant that instead of being unconnected, the purple coneflowers were surrounded by potential mates and went on to produce nearly double the number of seeds compared with other years. Wagenius says it’s not yet clear exactly how fires signal the flowers to get busy.

The new findings may help the people who manage prairies to better understand the different ways that fire affects the plants growing in these habitats, said Kathryn Yurkonis, a grassland ecologist who was not involved in the research. However, Yurkonis added, it remains to be shown how the fires influence the purple coneflower population. “This paper implies that making more seeds would mean more seeds would land on the soil and enter the population of plants — but they don’t actually examine that step,” she said. “I’d be curious to see whether this actually translates to more purple coneflowers.”

1. What is the basis for the research?

A．Prairies are easy to disappear.	B．Plants on a prairie are diverse.
C．Fire relates positively to prairie plants.	D．Without fire, flowers won’t bloom.

2. What does the author intend to convey with figures cited in paragraph two?

A．Wagenius’s team was committed indeed.

B．Samples of flowers were rich in number.

C．Time spent on the research was long.

D．The findings were relatively convincing.

3. What is paragraph 3 mainly about?

A．The result of plants being unconnected.

B．The influence of fires on prairie plants.

C．The process of prairie plants’ growing after fires.

D．The reason for plants’ blooming at the same time.

4. What is Kathryn Yurkonis’s attitude to the research finding?

A．Uninterested.

B．Prejudiced.

C．Objective.

D．Opposed.

3 . 听下面一段较长对话，回答以下小题。
1. Which plants are the woman’s favorites?

A．The red ones.

B．The pink ones.

C．The purple ones.

2. Why can’t the woman grow many plants in the house?

A．She is too busy to feed them.

B．There isn’t enough water.

C．There isn’t enough light.

3. What does the woman plan to do next?

A．Make a meal.

B．Water her plants.

C．Reach for a glass container.

4 . Dandelion (蒲公英)seeds are some of the best flyers in nature, catching the wind and spreading as far as 100 kilometers. Each dandelion seed is tied by a thin tube to around 100hairs, which form the parachute-like (类似降落伞的) structure, When seeds break free from the flower head, these hairs catch the wind and carry their seeds. This hairy parachute closes when the air is humid (潮湿的), which often means the wind is weak. In drier, windier conditions. dandelions widen their parachutes to better catch the wind so the seeds can fly freely.

However, in the past, nobody knew how they sense and respond to their environment so effectively.

Now researchers have uncovered the secret “thinking” behind dandelions’ spreading seeds. Their work. published in Nature Communications, found the seed-carrying parachutes open and close using something like actuators-devices that change signals into movement-without using active input of energy. The center of the parachutes senses the humidity of their immediate environment by absorbing water molecules (分子)from the air. Responding to these humidity signals. they either open their parachutes and fly away, or close their parachutes and stay put.

Study author Dr. Naomi Nakayama of the Department of Bioengineering who led the work said that their “findings reveal how the dandelion ensures the survival of its species by making perhaps the most important decision in a plant’s life—to stay or go seek a better habitat”.

“Understanding how dandelions work is fascinating because the dandelion is the foundation of ecosystems. It feeds insects and birds.” Nakayama says “So, the environmental sensitivity of their flight is an important topic for us to understand how nature will change in future climates.”

1. What can be learned from paragraph 1?

A．Dandelion seeds have a tube-like design.

B．A dandelion flower consists of 100 hairs.

C．Dandelion seeds begin to grow in dry weather.

D．The dandelion parachute closes on wet mornings.

2. What do researchers find about the dandelion?

A．Its hairs catch the wind easily.

B．Its actuator needs extra energy to function.

C．The middle of its parachute measures humidity.

D．Its actuator’s shape was changed by the wind.

3. Why do they study how dandelions work according to Nakayama?

A．To feed more insects and birds.	B．To better learn about climate change.
C．To explain their role in ecosystems.	D．To change dandelions’living environment.

4. What is the best title for the text?

A．Why dandelion seeds “prefer” the wind

B．How dandelions “tell” us their destinations

C．How dandelions “decide” to spread their seeds

D．Why dandelion seeds “create” parachute-like structure

5 . How to Care for Indoor Plants

If you’ve ever had an indoor plant that’s quickly withered (枯萎), you might believe that you don’t have a green thumb or you’re not cut out for growing plants.     1     The truth is that anyone can be a good plant owner, and it really isn't complicated, we promise. In this article, we'll walk you through everything you need to know to care for your indoor plants, from watering to sunlight requirements to fertilizer.

    2     If your soil is either too dry or overwatered, it can damage the plant’s roots and prevent the plant from growing. In some cases under or over watering your plant can also kill it. Plants with thick leaves require more water than plants with leathery leaves. There is no specific frequency that works for all indoor plants. Instead, what you must do is determine what kind of plant you have, and follow guidelines on how often to water it by doing research on its specific type.

Stick your finger in the soil to determine how wet it is below the surface. If you put your finger into the soil up to your joint, you can feel if your plant needs more water. If the soil feels damp, then you don’t need to water it.     3     If it feels dry then it’s likely you need to water it.

Use water that is at room temperature. 68F or 20C is the best temperature to keep the water that you’re using to water your plants.     4     After that, you are supposed to take some actions to make the plants grow comfortably.

Use a hand-held moisture (水分) meter to ensure water levels in your soil.     5     The mechanism explores the underlying soil to give you a reading on how hydrated (含水的) your soil is.

A．Keep potting soil moist, but not wet.

B．Indoor plants are not necessarily good for us.

C．Well, we’re here to tell you that’s not the case.

D．Test whether your finger is long enough to put into the soil.

E．You can use a thermometer to determine the temperature of the water.

F．Over-watering can lead to rotting of the root which you need to fix.

G．Moisture meters are the most accurate way to determine how hydrated your plants are.

6 . 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 ginkgo (银杏) tree is thought to be one of the oldest living trees,     1     (date) back to more than 290 million years ago. It is native     2     China, Japan and Korea, but it is also now grown in Europe and the United States. The earliest records of ginkgoes are found in Chinese herbology literature such as Compendium of Materia Medica.

Ginkgoes are large trees,     3     (normal) reaching a height of 20 — 35 meters, with some in China being over 50 meters. The adult tree has a large crown and long branches, and it is usually deep-rooted and resistant to wind and snow damage. With a combination of     4     (resistant) to diseases and insects, some of the trees     5     (claim) to be more than 2,500 years old.

With fan-shaped leaves, ginkgoes are green both on the top and bottom. But during autumn, they turn bright yellow and then fall, which make up     6     beautiful scene. Ginkgoes come in two sexes, with some trees being female     7     others male. The fruit has a soft, fleshy and yellow-brown outer layer     8     is attractive in appearance.

Because ginkgoes     9     (be) around for so long, people have used them for many purposes. It’s commonly used for memory and thought problems, vision problems and many other conditions, but there is no good scientific evidence     10     (support) most of these uses.

7 . A major benefit of growing your own tomatoes is variety. If you visit a garden center, you will find seeds and small starter plants for yellow tomatoes, purple tomatoes, huge tomatoes, and even very small tomatoes.

    1    . The most important things are to give the plants plenty of water, well- draining soil, heat and light. It is best to grow tomatoes in a place that receives at least six hours of sunlight each day. Removing weeds will keep pests and diseases away while giving the plants enough nutrients to produce fruit.

Tomatoes grow best in soil with a pH level between 6.0 and 6.8. If the pH reading is lower than 6.0, you can add about 2 cups of dolomitic lime (石灰) into the soil for each plant.

If you want to grow really big tomatoes, try following these seven tips from expert growers: Select tomato seeds with names like Big Zac or Bull’s Heart.     2    .

Start seeds early indoors and re-plant them into larger containers several times before moving them outdoors.     3    , removing leaves from the bottom one- third of plants and burying stems up to the next set of leaves. This will produce stronger plants.

Remove new flowers that develop at the top of the plant when older fruits near the bottom begin to grow.     4    . Pay close attention! Observe the plants daily for posts and diseases. React quickly to prevent problems.

Remove the small growths where the plant’s stems and branches meet. This will prevent them from taking away nutrients and shading developing fruit under them.

    5     instead of letting them develop into a shorter, wider shrub (灌木).

Finally, water, fertilize and weed!

A．Plant them deep each time

B．Rich soil benefits the growth

C．Tomatoes are not difficult to grow

D．Skills are demanding in growing tomatoes

E．Cut back the plants to keep only one main branch

F．They are all genetically designed to produce large fruit

G．This will force the plant to produce fewer but larger tomatoes

8 . If you’re interested in growing a small food garden at home, hydroponic (水栽法的) gardening provides a way to grow fresh, nutrient-rich food in a quickly-changing world with limited resources.

What is a hydroponic garden?

    1     Plants can grow indoors, year round, in less space than traditional soil- based gardens in it. This means if you live in a tiny apartment or don’t have an outdoor area, you can still grow fresh food.

How does hydroponic gardening work?

Plants need sunlight, water and nutrients to grow.     2     But the basis of hydroponics is rooted in growing the food in nutrient-enriched water. A hydroponic system can be programmed to ensure a plant receives sufficient water, nutrients, light and even the correct PH level to provide each plant with what it needs to survive and thrive.

What plants can grow hydroponically?

A variety of different foods can be grown in a hydroponic garden.     3     Similar to what you can grow in a backyard hanging garden, the more popular vegetables grown in hydroponics include leafy greens and lettuces (生菜) . However, more complex systems can produce fruiting vegetables such as tomatoes, cucumbers, peppers and more.

    4    

In addition to being able to grow food without soil and in small spaces, hydroponic gardening can contribute to solving social and environmental issues. In regions where people don’t have access to fresh vegetables, a hydroponic garden can be part of the solution. Hydroponic plants can grow 40% to 50% faster and produce 30% more than the plants growing in soil.     5     In some cases, you can grow produce that is even more nutrient.

A．Typically, plants get nutrients from soil.

B．What produce can a hydroponic garden offer?

C．What are the benefits of a hydroponic garden?

D．A hydroponic garden uses water instead of soil.

E．Microgreens are among the easiest plants to grow.

F．You can grow more produce in a shorter amount of time.

G．You can purchase a ready-to-go hydroponic garden or build your own.

9 . Antioxidants (抗氧化剂) are found naturally inn plants like blueberries, blackberries, and red cabbage. Scientists believe antioxidants may help prevent heart disease and help fight against diseases like diabetes. But tomatoes naturally only have a small amount of antioxidants in them.

British scientist Cathie Martin wanted to see if she could create tomatoes with lots of antioxidants by changing the DNA of a tomato plant.

A plant developed from specially created DNA is known as a GMO, or “genetically modified organism”. For hundreds of years, farmers have created new kinds of plants by mixing existing plants together using natural methods. GMO plants are different because the plants’ DNA has been changed by scientists. Scientists who do this usually think they’re improving the plants in some way.

After working on developing purple tomatoes for years, Dr. Martin’s experiment worked. Soon her plants were producing small purple tomatoes. Though the color is unusual, what’s really special about the tomatoes is that they have very high levels of antioxidants. Even better, the tomatoes remained fresh almost twice as long as normal tomatoes. Soon, Dr. Martin and other scientists created a company to promote the tomatoes.

The company tested its tomatoes on mice that were likely to get cancer. The mice who were fed the purple tomatoes lived about 30% longer than the mice who were fed normal tomatoes. Though that’s good news, experiments on mice don’t always predict what effects on humans will be like.

And GMO products weren’t popular with customers. Many people were scared by the idea that the foods weren’t “natural”. There are still questions about the effects of GMO crops on the environment and other plants, but most scientists agree that food from GMO crops is safe to eat.

On September 7, the government approved a GMO plant designed to target human health. Dr. Martin and her company plan to introduce the tomatoes at farmers’ markets across the US in 2023. They also hope to sell the seeds to people who want to grow their own.

1. What is the function of paragraph 1?

A．To define a concept.

B．To bring in the topic of the text.

C．To add background information.

D．To introduce the benefits of antioxidants.

2. What makes purple tomatoes really special?

A．Their medical value.	B．Their delicious flavor.
C．Their proper size.	D．Their pleasant color.

3. Why are GMO foods refused by people?

A．They are expensive to buy.

B．They are intended for animals.

C．They are thought to be harmful.

D．Their appearance isn’t appealing.

4. What is the government’s attitude towards GMO crops?

A．Opposed.

B．Unclear.

C．Positive.

D．Concemed.

10 . From Latin America to Sichuan province, chili peppers and their famous burning taste have become a worldwide sensation (热门) .But how could something that burns so hot possibly be any good for people?

In a study by researchers at Marshall University in the Us, scientists made the first complete description of capsaicin (辣椒素)—a chemical found in spicy chilies—and its anti-cancer properties. Although capsaicin is not normally a good medicine due to some negative properties such as its spicy flavor, the study found that there are ways to bring out its anti-cancer benefits while overcoming these negatives.

In nature, capsaicin evolved as a defense mechanism in plants to drive away unwanted animals while attracting those that could spread the seeds, such as birds which cannot taste or feel the spice. From a scientific point of view, capsaicin works by triggering a pain receptor called TRPV1, causing the body to react as if it had actually touched something hot and dangerous. Yet, this natural repellent (驱虫剂) for most animals has instead become a favorite food for many people, often called “chiliheads”.

So, what is it that attracts humans to capsaicin, chili peppers and spicy food in general? Besides its many health benefits — such as pain relief, weight loss, and body heat regulation—people love eating chili peppers precisely because it hits the pain receptors in just the right way.

As Scientific American noted: “People seem to enjoy — and actively seek out—many other sensations ... the sensation of falling provided by roller coasters or skydiving, the feelings of fear and anxiety while watching horror movies, the physical pain experienced upon jumping into icy water, or even the feelings of sadness that come while watching a tearjerker.”

So, the next time you bite into a hot chili pepper, remember: its not just healthy, but fun too!

1. What can we learn from the result of the study by researchers at Marshall University?

A．The study describes capsaicin for the first time.

B．Capsaicin contributes to the prevention of cancer.

C．There is a chemical called capsaicin in spicy chilis.

D．The negative features of capsaicin cannot be overcome.

2. How does capsaicin benefit plants?

A．It stops birds from eating plants.

B．It causes more seeds to be produced.

C．It attracts some animals to distribute seeds.

D．It helps plants survive in hot or dangerous situations.

3. How does the author prove spicy food is fun?

A．By illustration.	B．By statistics.
C．By comparison.	D．By definition.

4. What is the passage mainly about?

A．Why some people enjoy spicy food.	B．How chili peppers are so burning.
C．How plants benefit from capsaicin.	D．Where capsaicin can be found.