1 . A blue hole is a special kind of underwater cave found inland or in the sea, which forms when the earth above a cave falls in and water fills the space.

An inland blue hole’s water is very still and has different layers. A layer of fresh rainwater floats on top of salt water; the fresh water keeps oxygen from the atmosphere from reaching the salt water; brightly colored bacteria live where the two layers meet.

Diving into blue holes is very dangerous. Near the top of the blue hole, there is a layer of toxic gas, which causes itching, headache, and—in large amounts—death. Divers must also be fast. They have to get in and out of a cave before their oxygen runs out. Additionally, divers have to follow a guideline as they swim through a blue hole because it is very dark inside. Without the guideline, they may get lost.

If blue holes are so dangerous, why do explorers and scientists risk their lives to explore them? The reason is that these underwater caves can provide valuable scientific information. They provide clues about geology, archaeology, and biology. For example, some blue hole creatures probably haven’t changed for millions of years.

The blue holes could even provide clues about astrobiology. For example, divers have found bacteria there that can live without oxygen. Astrobiologist Kevin Hand says the bacteria may be similar to forms of life that might exist on Jupiter’s fourth largest moon, Europa. “Our study of life’s extremes on Earth,” he says, can help increase “our understanding of habitable environments off Earth.”

In addition, the oxygen-free environment of the blue holes preserves bones of humans and animals that fell into the caves long ago. By studying blue holes, we can understand what life was like in prehistoric times. As cave diver Kenny Broad says, “I can think of no other environment on Earth that is so challenging to explore and gives us back so much scientifically.”

2 . We found him a few weeks ago, walking along the road in the countryside. He was jumping on cars, and we thought maybe his family was camping somewhere nearby, ________ we passed him by. A few hours later, on our ________ trip, he was still in the same place, again, trying to get people to ________ for him. When he saw us, he laid down in the middle of the road, so we were unable to ________ him.

We stopped the car and looked around for a few minutes, trying to find his owner. But we ________ . Then we took a good look at the dog. He had no collar (项圈) and he was really ________ . We decided he was abandoned.

My husband said, “ ________ he doesn’t bite me when I try to pick him up to put him in the car, then we have a new dog.” The dog ________ joined us with no fight at all. He kept sticking his head between the two front seats and ________ us for picking him up.

The dog must have been ________ on the road for some time. He was so thin. So, we ________ him a lot over the next two weeks and he gained over twenty pounds. We took him to the doctor for ________ , who said the dog appears to be in good health. The vet (兽医) ________ the dog is about two or three years of age, from the condition of his teeth.

We do ________ this dog. He has been mistreated and yet, he still is so very sweet. He had no manners, but he is a ________ learner. He no longer tries to get on the bed, but he does like sitting in chairs. Since then, he has become a member of our family.

Some theme parks not only make people feel     1     (amaze) but also are educational. Take the Polynesian Cultural Center (PCC) in Hawaii for example. It not only shows visitors the Polynesian way of life but also     2     (protect) their skills and culture for the future. Polynesia is     3     name given to the groups of small islands that are spread about the Pacific Ocean.

The     4     (villager) from many island communities come to the Polynesian island villages to show visitors their styles of dress and different customs. They are the places     5     visitors can learn how the islanders make clothes from bark (树皮) and how the islanders climb very tall trees with their bare feet.

One of the important skills for Polynesians is boat-building. It allows the islanders     6     (explore) all the islands in the Polynesian Triangle.     7     (obvious), they were sea travellers in their history moving     8     island to island. They were     9     (confidence) of finding their way by     10     (use) the smell of the wind, the movements of the fish and seaweed, and the heights and directions of the waves.

Located at the western part of Hangzhou, just under 5km away from the West Lake, Xixi National Wetland Park distinguishes itself as     1     exceptional urban place. This park is a pioneering example of how urban life combines agriculture with culture, making it a     2     (real) unique destination. Along with Xihu and Xiling famous, respectively, for their natural scenery    3     cultural heritage, Xixi National Wetland Park is one of the celebrated “Three Xi’s of Hangzhou”.

    4    (cover) a vast area, the park consists of three causeways(堤道) and features ten famous sights. Nearly 70% of the park is occupied by river ports, ponds and small lakes,     5     explains a wetland environment. These waterways cross the park, dividing it into distinct     6     (section): the east, the west, and the central part.

So far, the government     7     (establish) ecological protection zones as well as a sightseeing zone.     8     addition, visitors can explore the Wetland Science Exhibition Hall at the park’s main entrance conveniently.

The Xixi wetlands is an area of unmatched peace and quiet — filled with history and natural     9     (beautiful). The only true thing that can be said of the Xixi wetlands     10     (be) that if you haven’t seen them, you haven’t really seen Hangzhou.

Twin giant pandas have been born at a breeding (繁殖) center in southwestern China,    1    is a sign of progress for the endangered species as they struggle for survival due to occupation on their land by agriculture    2    industry.

The male and female baby pandas, born on Tuesday at the Qinling Panda Research Center in Shaanxi Province, are the second pair of twins born to    3     (they) mother, Qin Qin. She was also born at the center and    4     (previous) gave birth to twin females in 2020.

Chinese researchers for years have been working    5     (promote) the population of the animals, which reproduce rarely in the wild and rely    6    a diet of bamboo in the    7     (mountain) of southwestern China.

The efforts have paid off, with some captive-bred pandas being released into the wild. The population of wild pandas    8     (increase) over the past few years,    9     (reach) an estimated 1,800. About 500 others live in zoos and reserves, while the    10     (major) live in the mountainous, heavily forested province of Sichuan.

7 . The first time ever I realized that plastic was a serious matter for our planet was during a road trip in Western Australia, almost 12 years ago.

We________at a supermarket along the Coral Bay coast to buy some groceries and the lady at the counter told us they didn’t sell any shopping bags in order to prevent plastic in the________and to help preserving the endangered turtles living in that area. After a first reaction of surprise, we________all our shopping in our arms and left.

This was just one of the many experiences I’ve lived that made me more________about my impact and pushed me to adopt different habits to live and________more sustainably.

Our trip to Borneo was another life-changing________that has strengthened my resolution to a zero-waste lifestyle. While traveling in some Asian countries, we came to know that________drinkable water was always a challenge. So we had to travel with our water bottle, and we________to avoid using plastic during our trip.

Besides, we were also________impressed by our stay on Libaran Island. A sustainable turtle conservation________and the community had made big efforts to________ the beaches and creatively re-use plastic for ten years. Despite that, the shore is________daily with tons of plastic coming from the tides.

Facing this global issue________, raised in me a feeling of sadness and anger that soon turned into________: to do as much as possible to reduce plastic in our life. Small changes can________a difference!