If you go out to the fields at night in spring or summer, you can hear frogs singing     1    (happy) here and there. It seems as if they were performing a field group singing.

The frog is a good and useful creature that benefits human beings. They can catch fast-moving     2     (insect). Each frog eats a large number of pests (害虫) that are     3     (harm) to crops. This little creature is regarded as “the natural enemy of pests”.

But now frogs     4     (get) fewer and fewer. This is     5     they are killed and put on the table as a delicious dish by their chief enemy, human beings. It is a shameless and cruel act, isn’t it?

The cause that is responsible     6     the rapid reduction of frogs is that farmers use insect killers to kill pests and frogs get killed as a result of drinking poisoned water while     7     (eat) poison-killed insects.

Something must be done as soon as possible     8     (save) frogs. If we don’t punish those     9     sell and kill frogs to make money, then one day all of us     10     (punish) by nature for failing to keep them.

2 . The city of Venice, Italy, has finally made a long-awaited decision. Starting on August 1, 2021, cruise ships (游轮) will no longer be allowed to enter the city’s waters.

Contrary to popular opinion, these cruise ship visitors contribute relatively little to the local tourism economy. The New York Times reported cruise ship passengers add up to 73% of visitors, but contribute a mere 18% of tourism dollars. The percentage is inverted for people who spend at least one night at a hotel; they represent 14% of visitors, but 48% of the business.

Many people are overjoyed by the news, especially environmental activists. Firstly, the cruise ships would disturb the waterways and erode (侵蚀) the foundations of already weak buildings. A 2019 study published in Nature found the waves created by large ships could “redistribute industrial pollutants already present in the waters.” Others have said these same waves made huge holes in the underwater bottoms of buildings, making them unstable. Furthermore, when canals are deepened in order to allow larger boats, it destroys coastal habitats and makes floods worse. This is part of the reason why, in recent years, Venice has experienced terrible flooding that completely flooded St. Mark’s Square and other landmarks.

The announcement came as a surprise as many did not expect the regional government to act so quickly. In April a similar ban was issued, but it depended on finding an alternative port for the ships—a requirement that local people complained could take years to achieve. The announcement made last week, however, did away with that condition, allowing the city to move forward quickly with the ban.

4 . A method to transform a commonly thrown-away plastic to a resin (树脂) used in 3D printing could allow for making better use of plastic waste. A team of Washington State University researchers developed a simple and efficient way to transform polylactic acid (PLA)(聚乳酸), a bio-based plastic used in products such as filament, plastic silverware and food packaging to a high-quality resin.

“We found a way to immediately turn this into something that’s stronger and better, and we hope that will provide people the inspiration to upcycle this stuff instead of just throw it away,” said Yu-Chung Chang, a postdoctoral researcher in the WSU School of Mechanical and Materials Engineering and a co-corresponding author on the work. “We made stronger materials just straight out of trash. We believe this could be a great opportunity.”

Although it’s bio-based, PLA, which is categorized as a number 7 plastic, doesn’t break down easily. It can float in fresh or salt water for a year without degrading (降解). It is also rarely recycled because like many plastics, when it’s melted down and re-formed, it doesn’t perform as well as the original version and becomes less valuable.

“It’s biodegradable and compostable, but once you look into it, it turns out that it can take up to 100 years for it to rot away in a landfill,” Chang said. “In reality, it still creates a lot of pollution. We want to make sure that when we do start producing PLA on the milliontons scale, we will know how to deal with it.”

While the researchers focused on PLA for the study, they hope to apply the work to poly-ethylene terephthalate (PET) (涤纶树脂), which is more common than PLA and has a similar chemical structure and presents a bigger waste problem. They have filed a temporary patent and are working to further optimize (优化) the process. The researchers are also looking into other applications for the upcycling method.

5 . When most of us think of sand, we immediately think of sunny beaches and summer holidays. But actually it’s in pretty much everything that surrounds us in our everyday lives, from the walls of our homes to the glass bottles in out kitchens and even the mobile phones in our hands. Sand is the second most used resource in the world after water: it accounts for more than two-thirds of everything that’s being dug out of the ground. But there isn’t a limitless supply. In fact, a UN report says we might be running out.

According to the report, we use an estimated 15 billion tons of sand every year in the construction industry alone. That’s enough to build a 20m×20m wall around the equator (赤道) every year. However, sand can take tens of thousands of years to form (形成): the process starts with rock being eroded (侵蚀) in the mountains and ends, eventually, with sand being in river beds, on beaches and on the seafloor.

Sand is heavy and difficult to transport, so in developing countries, sand is often mined from the nearest convenient source, and quite often that means a river bed or beach. But beaches and rivers are delicately balanced ecosystems and when a large amount of sand is removed, the balance is upset. The smallest fish, which eat organic matter on the sand in river beds, form the base of the food chain in a river. If this sand is removed, so is the source of food for the bottom feeders. All organisms in a food chain share the joys and the sorrows. Thus, when they disappear, so does the food for the larger fish which would have been caught and eaten, or sold by fishermen.

It is high time we took into consideration the big problem concerning the tiny thing. More and more conservationists are calling for new choices to replace sand, especially in the construction industry.

8 . You can see a sea turtle named Hermanan octopus(章鱼) called Octavia, and a seal named Lidia at the Smithsonians National Zoo in Washington DC. Rather than real animals, they are actually artworks made out of plastic trash from the ocean.

These artworks are part of a traveling exhibit called “Washed Ashore: Art to Save the Sea”. The Washed Ashore project, led by the artist called Pozzi, works to raise awareness about plastic pollution in Earth’s oceans.

More than 315 billion pounds of plastic litter the world’s oceans today. Most of the plastic is garbage from towns and cities, as well as trash that people leave on beaches. Rainwater, winds, and high tides bring the trash into the ocean or into rivers that lead to the ocean. Once it is under the waves, the plastic begins to break up into smaller and smaller pieces.

Thousands of sea animals die each year from eating plastic bags and other things. Each year, millions more pounds of plastic end up in the ocean. A recent study found that if that continues, by 2050 the total weight of plastic will be more than that of all the fish in the ocean.

The Washed Ashore project is working to stop that from happening. Since 2010, Washed Ashore volunteers have collected 38000 pounds of plastic trash from more than 300 miles of beaches. They helped Pozzi create more than 60 artworks of sea creatures harmed by plastic pollution.

“These artworks are a powerful reminder of our personal role and global responsibility in preserving biodiversity(生物多样性)on land and in the sea,” says Dennis Kelly, director of the National Zoo.

10 . With greater climate catastrophe (气候突变) on Earth, it is natural for us to make every effort to stop the potential floods, snowstorms, and alarming reports from scientists. For many of us (myself included), part of that means running out to buy reusable straws, organic cleaners, and packaging-free products.

However, before you are delighted at “green” purchases, take a second to consider the results of a new study from Arizona University. By comparing the shopping habits, mental health and environmental impact of young people, the researchers reconfirmed a principle: Buying less beats buying “green” stuff without effort. And that is true whether you are looking at the impact that your purchases have on the Earth or on your own happiness.

It should not come as a shock that simply consuming less is better for the planet. After all, every new item a factory yields requires some resources to produce. Take plastic bag bans for instance. If your city is getting rid of single-use shopping bags, it can be attractive to pay for a fashionable organic cotton bag hanging in the check-out line of your local supermarket. However, experts insist that growing cotton is actually no better for the Earth than producing the conventional plastic bags. Then what is your best bet for carrying your groceries if you care about sustainability? Any bag you already own.

It is not just the Earth that will be happier if you buy less. You will feel more contented too, according to the new study. “People believe that they might well be self-satisfied about becoming environmentally conscious through ‘green’ buying patterns, but it doesn’t seem to be that way”, said the lead researcher Sabrina Helm. “Reduced consumption has effects on increased well-being, but we don’t see that with ‘green’ consumption.”

“Owning every new ‘green’ product on the market might make you feel contented, but if you relieve yourself of that burden of ownership, most people report feeling a lot better,” said Helm.