2 . WHAT ARE RIP CURRENTS?

Rip currents are like the rivers of the sea, transporting water near the shore back out into the ocean depths. The presence of these currents can be hidden by the wild movements of the surrounding waves. This means that as well as carrying seaweed and pieces of materials quickly out to sea, they can rapidly sweep away even the strongest swimmers. Around 80 percent of all lifeguard rescues are caused by powerful rip currents pulling a swimmer into danger.

If you find yourself being pulled out to sea by an unsuspected rip current, you should remain calm, focus on staying afloat and, if you can, swim parallel to the shore. Your instincts might tell you to swim towards land, as this is where you’re aiming to get to, but the current will be too strong to swim against. Instead, aim to move across the current and into slower flowing water next to it. A rip current may only pull you just past the breaking waves, but in some cases they can take you hundreds of metres offshore. The strength of currents can be hard to predict, so it’s safest to stay on lifeguarded beaches and not to swim if you see any indication of a rip current.

Walking around a digital exhibit hall in Yongle Palace in Yuncheng, Shanxi province, it is difficult not to be amazed and     1     (inspire) by 3D printing, digital murals (壁画) and other exhibition projects. All this is thanks to the great effort     2     has been put into digitally preserving the Yongle Palace murals.

Yongle Palace (palace of eternal joy), one of the three biggest Taoist temples in China, is the     3     (large) of all Taoist temples     4     (remain) from the Yuan Dynasty (1279-1368) and was among the first national key cultural relics protection items.

In 2016 experts found that its murals were deteriorating (恶化) and that the wooden     5     (component) of the four halls were deformed and cracked, and     6     rescue operation then began.

A digital collection of murals, buildings and other movable cultural relics was created and     7     (eventual) made available to the public on the internet.

Xi Jiulong, head of the Yongle Palace mural art protection research institute, says technological intervention has helped bring life to history to help the public better understand it.

Visitors could also immerse     8     (them) in the splendid artworks and learn more about the antiquities by scanning the QR code attached     9     each item.

Over the past two years digital exhibitions of murals in Yongle Palace     10     (hold) around China to great acclaim (赞扬，称赞).

Natural Domes

A dome is a curved formation or structure. It is shaped like half of a sphere. Imagine cutting an orange in half, and placing it cut-side-down on a table. This is the shape of a dome, although most domes in nature are not     1     rounded.

Some natural domes develop when magma(岩浆)from deep within the Earth pushes up    2     rock layers. This type of geologic dome can     3     as magma intrudes between two layers of sedimentary rock. The magma creates a dome or triangle shape as it pushes the other layers apart. The hardened magma that forms this type of dome is called “laccolith”.

Lava domes form as magma     4     atop volcanic vents(火山口). In the Chaitn Volcano in Chile, an ongoing eruption that began in 2008 is forming a lava dome next to another one that filled the crater when the volcano erupted 9, 400 years ago.

Another kind of natural dome is shaped    5     by weathering and erosion, which cause curved sheets of rock to separate from a large rock mass. The Cima Dome in the MojaveDesert, in the U. S. state of California, was once a mountain. Over time, weathering and erosion     6     away the mountain and smoothed it into a rounded dome.

Salt domes result when rock salt rises through overlying sedimentary rock. Salt    7     up as ancient seas dry up over time. Eventually, sediments form over this layer of salt. Salt is less dense than most other rocks, and it slowly moves upward toward the surface, forming a dome-shaped hill. One of the most famous salt domes is Avery Island, in the U. S. state of Louisiana. Avery Island is a salt dome     8     by low-lying swamps(沼泽地)of the Mississippi River delta. Eventually, these salt domes can break through the surface rock layers. Actually, salt domes are important sites for industry. Salt is a valuable     9     used in the production of plastics, pesticides, preservatives, and fire extinguishing equipment. Moreover, Salt domes     10     oil between layers of rock so that oil wells can drill into it and extract oil.

8 . With no special equipment, no fences and no watering, two abandoned agricultural fields in the UK have been rewilded (重新野化), in large part due to the efforts of jays, which actually “engineered” these new woodlands. Researchers now hope that rewilding projects can take a more natural and hands-off approach and that jays can shed some of their bad reputations.

The two fields, which researchers have called the New Wilderness and the Old Wilderness, had been abandoned in 1996 and 1961 respectively. The former was a bare field, while the latter was grassland—both lay next to ancient woodlands. Researchers had suspected that the fields would gradually return to wilderness, but it was impressive to see just how quickly this happened, and how much of it was owed to birds.

Using aerial data, the researchers monitored the two sites. After just 24 years, the New Wilderness had grown into a young, healthy wood with 132 live trees per hectare, over half of which (57%) were oaks. Meanwhile, the Old Wilderness resembled a mature woodland after 39 years, with 390 trees per hectare.

“This native woodland restoration was approaching the structure (but not the species composition) of long-established woodlands within six decades,” the researchers explained in the study.

Part of this reforestation was done by the wind, and researchers suspect that previous ground disturbance may have aided the woodland establishment—which is good news, as it would suggest that agricultural areas may be reforested faster than anticipated. However, animals—Eurasian jays, thrushes, wood mice, and squirrels—also played an important role in helping the forests take shape. This handful of species provided much of the natural regeneration needed for the forest to develop. Jays, in particular, seem to have done a lot of heavy lifting.

Canada, which     1     (make) up of ten provinces and three territories, is a broad and beautiful country     2     (stretch) from the Atlantic to the Pacific Ocean. There is great diversity in geography in Canada. It includes the grand Rocky Mountains     3     high peaks and deep valleys carved by ice and water, ancient slow-moving glaciers hugging the land and a huge variety of wildlife     4     (wander) the remote forests.

Apart from its geographical diversity, Canada’s many rural areas and urban centers reflect the diversity of its residents. Some of Canada’s     5     (early) settlers,       6     are thought to be ancestors of the indigenous peoples, crossed the Bering Strait by means of a land bridge from a place now known as Siberia. Today, Canada reflects a vast     7     (combine) of ethnic backgrounds. About one out of five of its population is foreign-born.

This ethnic variety, in turn, brings     8     cultural diversity. Should you find yourself in one of these     9     (subculture), languages, cuisine, architecture, art and music will define your encounter. As you are exposed     10     diverse cultures, you may feel transported through time and space.