A new study suggests Jupiter’s icy moon (卫星) Europa produces much less oxygen than previously thought. The study was based on the data     1     (collect) by NASA’s Juno spacecraft.

The study involved Juno’s instruments measuring levels of oxygen     2     hydrogen molecules (分子) coming from Europa’s atmosphere. The data showed the icy moon produces about 1,000 tons of oxygen every 24 hours. NASA said that would be enough amount     3     (keep) a million humans breathing for a day.

However, the space agency noted those estimates of oxygen were much less than those measured in earlier studies about the moon. Europa is a little     4     (small) than the Earth’s moon. But it is still one of the largest moons in     5     (we) solar system. NASA observations have suggested     6     ocean exists beneath the thick layer of ice on Europa’s surface. Scientists estimate the moon’s ocean may contain a large amount of water,     7     is twice as the Earth’s oceans.

Since Europa was believed to have a large ocean under its surface,     8     (researcher) in the past identified it as a good candidate to hold the right conditions to support some form of life. That data came     9     (main) from telescope observations of oxygen levels existing in the moon’s icy surface. The new lower estimates of oxygen do not support the earlier observations. The team involved in the study said, in the future, more research     10     (need) to confirm the latest findings.

On March 31, the Eiffel Tower celebrated its 130th anniversary since it opened.     1    (original) planned to last only 20 years, the people of Paris wisely decided to keep it standing,    2     (recognize) its importance. Millions of people     3     (visit) the tower so far, according to its official website.

The tower was created by the French engineer Gustave Eiffel and was first intended as the main entrance     4     the 1889 World’s Fair. It was built in a little over two years and faced criticism from some locals initially. However, it quickly captured the attention of fair visitors, attracting more than two million people. It also had a     5     (practice) use as a radio antenna during World War I.

Visitors today can choose to climb 1,665 steps or take one of the original elevator cars    6     (reach) the top. At the top of the tower,     7     the tower’s administrative office is located, guests can enjoy a drink at the champagne bar on the top floor.

Today, the Eiffel Tower is a symbol of France, representing a feeling of pride and thankfulness. It is a global icon that can bring together people from different     8    (background). The tower is not only     9     popular tourist destination but also a widely recognized symbol, a     10     (believe) held by many who appreciate its enduring charm.

It is not every day that scientists explore a beautifully protected ancient forest deep inside a sinkhole (落水洞).

Such a     1     (discover) was made in a wonderful karst mountain range in Guangxi when a team of explorers     2     (enter) the 192-metre-deep sinkhole on May 6 and found a forest that had towering trees.

The sinkhole also had other plants     3     were “shoulder-height”, said Chen Lixin, the leader of the research team, in an interview. Chen added that he would not be     4     (surprise) if undiscovered plants and animals lived in the sinkhole.

Apart from being deep, the sinkhole is 306 metres long     5     150 metres wide, meaning it can     6     (see) as a large sinkhole.

The scientists said the forest was an ancient woodland and it had probably never been disturbed (打扰) by human activity. These types     7     woodlands can be extremely important because they form an ecosystem (生态系统) without human influence.

China is home to the world’s deepest sinkhole, Xiaozhai Tiankeng, which is 662 metres deep and was     8     (main) caused by a great underground river that still runs below the natural wonder.

In the Bahamas, Dean’s Blue Hole is another sinkhole famous for     9     (it) natural environment, making it one of the world’s top tourist     10     (destination).

In July 2019, Shanghai became the first city in China     1     (make) household waste sorting (分类) compulsory (强制的). A number of other cities have followed in Shanghai’s footsteps by     2     (introduce) compulsory household and workplace rubbish sorting in the following years.     3     (actual), about 300 cities in China have carried out rubbish sorting programs at present, with a community coverage rate of 82.5%.

According to Hua Lei, a volunteer involved in rubbish sorting, the practice     4     (become) part of the daily lives of local residents (居民) over the past five years. Young people have played     5     important role in raising knowledge and educating the community, using creative     6     (way) such as short plays to teach older residents about rubbish sorting. Additionally, students     7     have learned about waste management at school have shared their knowledge     8     their families, further spreading the message.

Through these joint efforts, China is making progress in rubbish sorting and recycling. More residents     9     (encourage) to use rubbish sorting habits to contribute to a cleaner and     10     (good) living environment for its citizens.

Shanghai Oriental Pearl Tower     1     (locate) in Pudong Park in Lujiazui, Pudong New Area, Shanghai.     2     (surround) by the Yangpu Bridge in the northeast and the Nanpu Bridge in the southwest, it creates a picture of “twin dragons playing with pearls”. The entire scene is a photographic jewel that excites the imagination and attracts thousands of visitors year-round.

This 468-meter-high tower is the world’s sixth and China’s second     3     (tall) TV and radio tower. However, even more charming than its height is     4     unique architectural design that makes Oriental Pearl Tower one of the most attractive     5     (place).

Visitors travel up and down the Oriental Pearl Tower in double-decker elevators     6    can hold up to fifty people     7     the rate of seven meters per second. Once you reach your destination, you will be amazed at the     8     (various) of activities available as the various spheres and columns     9     (actual) house places of interest, commerce and recreation. It is amazing that this Oriental Pearl TV Tower     10     (combine) ancient concepts such as the spherical pearls with 21st Century technology, commerce, recreation, education and conference facilities.

The panda population in the wild     1     (rise) in the last 20 years, which reflects the pandas’ improved living conditions and China’s efforts in keeping their habitats integrated. Now, it’s time     2     (release) the cubs (幼兽) into the wild.

A gene exchange between captive (被圈养的) and wild pandas aimed at better     3     (protect) genetic diversity is a major project at the China Conservation and Research Center for Giant Panda, according to He Shengshan, a guardian and expert at the center. He said wild pandas live in     4     wide range of areas, so the population is divided into 33 groups     5     (base) on their location.

“This is similar to human villages or tribes. Some large groups in the wild may have     6     (hundred) of pandas, while smaller groups may have just a few dozen. After investigation, we found that of the 33 communities, 22 communities had     7     (few) than 30 giant pandas,” said He Shengshan. “Because pandas have poor ability to travel and there are mountains, human activities, highways and railway tracks, giant panda groups can’t communicate with each other, and those with small populations are still at risk of     8     (extinct) over time.”

The training for release is a long process     9     starts before a cub is born. And usually it is divided into two stages. The first lasts from the mother’s pregnancy     10     the cub is about 1 year old, while the second stage runs from the cub to a panda about 1 to 2 years old.