1 . Pumpkins (南瓜) have all shapes and sizes and have colors of golden orange, white and green. Cooked in a pie, they are symbols of autumn that are grown in every county of Washington.

U.S. farmers grow more than a billion pounds of pumpkins every year, and many famers use sheets (膜) of plastic blocking the grass and preventing water loss to make their plants grow well. In the country, farmers use about a billion pounds of plastic every year. Unfortunately, that plastic is thrown away finally, and in some areas, burned in the fields.

For several years, Carol Miles has studied a new product—the soil-biodegradable (土壤生物降解的) plastic cover that can be left in the ground after harvest, then broken down by things in the soil. “You don't need to pull it out of the field and throw it away every autumn, saving time and money,” Miles said.

Most pumpkins grow along vines (藤蔓) that spread through the grass-blocking cover, and Miles wanted to see how pumpkin fruit performed over the plastic cover. That brought a challenge: the soil-biodegradable cover stuck to the bottom of the fruit.

“We have a lot of dew (露水) in the morning, and we found that if we let the fruit dry after harvest, the cover would stick more strongly to the pumpkins,” Miles said. “Nobody wants plastic stuck to pumpkins, even if it's biodegradable. But if you wipe the fruit before the dew dries, the plastic comes right off.”

Farmers who grow plants that don't set fruit on plastic covers won't meet this challenge. For those who do, it means an extra step that they'll have to weigh against advantages and disadvantages for the development.

“Challenges aside, working with this crop can bring on a happy picture,” the farmer Tymon said. “Pumpkins are great. They have bright colors, and are really fun to work with.”

1. How did farmers deal with the sheets of plastic in old farming method?

A．They collected them and recycled them.

B．They burned them or threw them away.

C．They covered them under the ground.

D．They broke down them and buried them in the soil.

2. What's the advantage of Mile's new product?

A．It prevents water loss.

B．It blocks the grass.

C．It is stuck to pumpkins easily.

D．It's environment-friendly.

3. How can farmers do to prevent the plastic sticking to pumpkins?

A．Let the pumpkins break down plastic sheets.

B．Wipe the dew from the plastic cover.

C．Clean the pumpkins when they're wet.

D．Put some powder on the plastic sheets.

4. What does the underlined words “weigh against” means?

A．Balance against.	B．Fight against.
C．Remove.	D．Measure.

2 . To address the plastic pollution troubling the world’s seas and waterways, Cornell University chemists have developed a new polymer (聚合物) that can degrade (降解) plastic when exposed to ultraviolet radiation, according to the research published in the Journal of the American Chemical Society.

“We have created a new plastic that has the mechanical properties required by commercial fishing gear. If it eventually gets lost in the water environment, this material can degrade on a realistic time scale,” said lead researcher Bryce Lipinski, professor of chemistry and chemical biology at Cornell University. “This material could effectively reduce persistent plastic accumulation in the environment.”

Commercial fishing contributes to about half of all floating plastic waste that ends up in the oceans. Fishing nets and ropes are primarily made from three kinds of polymers, none of which easily degrade. “While research of degradable plastics has received much attention in recent years,” Lipinski said, “obtaining a material with a mechanical strength comparable to commercial plastic remains a difficult challenge.”

Coates and his research team have spent the past 15 years developing the new plastic called isotactic polypropylene oxide, or iPPO. While its original discovery was in 1949, the mechanical strength of this material was unknown before this recent work. The high isotacticity and polymer chain length of their material makes it different from previous plastics and provides its mechanical strength.

Lipinski and other scientists want no race of the polymer to be left in the environment. He notes there is precedent (先例) for the biodegradation of small chains of iPPO which could effectively make it disappear and ongoing efforts aim to prove this.

1. What is the feature about the new polymer?

A．It can solve the problem of plastic consumption.

B．It can degrade plastic waste in the sea water.

C．It has been developed to solve plastic pollution.

D．It has been developed to lower fishing costs.

2. What can we infer from paragraph 3?

A．It requires great effort to invent the new plastic.

B．Fishing should be forbidden in the sea.

C．Fishing nets and ropes are not the major pollution source.

D．Degradable plastics were not paid attention to until recent years.

3. What did the recent study find about iPPO?

A．Its original discovery.	B．Its mechanical properties.
C．Its complex structure.	D．Its mechanical strength.

4. What is Lipinski’s attitude towards the future of iPPO?

A．Doubtful.	B．Promising.
C．Unconcerned.	D．Disapproval.

3 . Running after fireflies （萤火虫）on a warm summer night might become a rare childhood memory if humans don't take action. There are over 2,000 different firefly species around the world, but their populations are decreasing due to artificial light pollution, pesticides （杀虫剂）and smaller habitat size.

A team of Tufts University-led researchers surveyed scientists and conservationists about the threats to firefly populations around the world. According to the study, one of the main threats to fireflies in East Asia and South America is artificial light. Fireflies light up to attract mates, but they can easily mistake human-made lights as potential partners. Adult fireflies typically live only a few days, which doesn't give them long to find a mate.

Humans' destroying the insects' natural habitats creates another threat. During their larval phase （幼虫期），Malaysian fireflies live in riverside bushes that are often pulled out for human-made fish farms. In Europe, Lampyris fireflies are finding less food to eat due to the growing urbanization of what were once woods and farmlands. In Malaysia, adult pteroptyx fireflies that usually prefer to mate in specific trees next to rivers have to find new mating areas because the trees are being knocked down for farmhouses.

The study also looked at the effects of climate change, tourism, invasive （侵入的）species and water pollution. On a positive note, while fireflies around the world seem to be suffering from the previously mentioned issues, Big Dipper fireflies living in the US happen to be booming. "Those guys can survive pretty much anywhere,said Sara Lewis, a biologist from Tufts University.

The study urges countries where firefly populations are dwindling to take measures to preserve suitable habitats, lessen light pollution, reduce use of pesticides and develop better guidelines for tourism around known firefly areas.

1. What mainly causes the drop of the firefly population in East Asia?

A．Light pollution.	B．Habitat loss.
C．Climate change.	D．Food shortage.

2. Which of the following is more likely to adapt to the environment?

A．The Malaysian firefly.	B．The Lampyris firefly.
C．The Pteroptyx firefly.	D．The Big Dipper firefly.

3. What does the underlined word “dwindling” in paragraph 5 mean?

A．on the rise	B．on the decrease
C．under control	D．out of control

4. What does the text mainly talk about?

A．Watching fireflies is a rare childhood memory.

B．Cooperation is the key to firefly protection.

C．Urbanization becomes a main threat to fireflies.

D．Human activities lead to less firefly population.