3 . Scientists have solved a puzzle about modern humans, after research showed that a famous skull of a human ancestor found in South Africa is a million years older than experts thought. This discovery has changed what we know of human history.

The skull, which scientists have named “Mrs Ples”, is from an ape-like human relative from a species called Australopithecus africanus (南方古猿). It was found near Johannesburg in 1947 and, based on evidence from its surroundings, was thought to be between 2. 1 and 2. 6 million years old. This puzzled scientists, because although Mrs Ples looks like a possible early ancestor of early humans, the first true humans had already evolved by the time she apparently lived. For this reason, scientists had decided that Australopithecus afarensis, a similar species from East Africa that lived about 3.5 million years ago, was our most likely ancestor instead.

To get a more accurate age for Mrs Ples, a team led by Professor Darryl Granger of Purdue University in Indiana, US, used a new method to date the sandy rocks where the skull lay. They measured the amount of certain chemicals in rocks, which form at a steady rate when they are exposed to cosmic rays (宇宙射线) on Earth’s surface. Once rocks are buried, these chemicals stop forming and slowly disappear;the surviving amount reveals how much time has passed since the rock (or bones) were on the surface.

The new study shows that Mrs Ples and other australopithecine bones nearby are between 3.4 and 3.7 million years old. This means they lived at the same time as their East African relatives, so that either group could have given rise to modern humans. However, team member Dr Laurent Bruxelles pointed out that over millions of years, at only 2,500 miles away, these groups had plenty of time to travel and to breed with each other. In other words, the groups could quite easily have met, had children together and both been part of the history of modern humans.

Peru is a country on the Pacific coast of South America with three main     1     (area). In the 1400s and 1500s, Peru was the centre of the ancient Inca Empire. Spain     2     (control) Peru in the 16th century and ruled it until 1821.

Fly from Cusco into the Amazon rainforest, where you take a boat to get to your accommodation in     3     middle of the forest. Then spend three days     4     (hike) and exploring nature.

You will be     5     (amaze) by Machu Picchu.     6     (especial) amazing is the Incas’ dry stone method of building. Stones     7     (cut) to exact sizes so that nothing was needed to hold walls together other than the perfect fit of the stones.

Cusco was the capital of the Inca Empire from the 13th     8     the 16th century. There, you can enjoy the unique Spanish and local Indian culture. Stay in a local hotel, visit the museums, admire the architecture, enjoy the excellent local food, and go     9     (shop) at the local markets.

When arriving in Lake Titicaca, a boat will take you to a local Uros family on an island for three days. Both the island and the Uros homes are made     10     water plants from the lake.

6 . Sometimes shipwrecks（沉船）contain sunken treasure, loads of gold or jewelry. Other shipwrecks are themselves the treasure—the stories of their ill-fated voyages creating a legend that makes them sparkle far more than any gold or precious stones.

The wreck of HMS Endurance, which has finally been located deep beneath the icy seas of Antarctica after being lost 107 years ago, was arguably the most valuable shipwreck ever sought. That’s because its discovery adds another thrilling new chapter to an already fascinating tale of perseverance and survival that has echoed down the decades and still inspires today.

Incredibly well preserved at a depth of almost two miles, the ship is little changed from the day in November 1914 when it finally sank beneath the ice. Endurance became embedded in ice while crossing Antarctica’s Weddell Sea. The video shot by underwater search vehicles shows painted timbers, an undamaged guardrail（护栏）and the name “Endurance” written above the five-pointed symbol of a polar star.

“I tell you, you would have to be made of stone not to feel a bit soft at the sight of that star and the name above,” Mensun Bound, the mission’s marine archaeologist, told the BBC. “You can see a porthole（舷窗）that is in Shackleton’s cabin. At that moment, you really do feel the breath of the great man upon the back of your neck.” Shackleton’s leadership was crucial to getting his men out alive. The reason why Shackleton is still applauded as a great man becomes obvious when you consider what he achieved in the face of disasters and hardships during his 1914-16 expedition. The practicality and humanity he showed in the face of severe situations was arguably praised.

People have been exploring the secrets of ancient Maya civilisation for     1     (age). It is the lack of modern technology in Maya society     2     makes its achievements mysterious. The Maya built     3     (impress) palaces and temples without the use of wheels and metal tools. They knew a lot about mathematics and astronomy. What’s     4     (much), they invented a writing system, which was so complex that no one has been able to interpret it completely. Its civilisation was     5     its peak by 700 AD. But it began to mysteriously decline within just a couple of generations.

People are searching for the reason why Maya civilisation     6     (collapse). Researchers have different opinions about it. Maybe it is due to a natural disaster or a deadly disease. Some research seems to show that the Maya people themselves may have played     7     role in their downfall. Turning wetlands into fields for agriculture, they reduced     8     (they) ability to cope with natural disasters. Therefore, a series of droughts occurred around 900 AD,     9     (lead) to food shortages, conflicts and     10     ( eventual) the downfall of the cities.

The rise and fall of this civilisation not only give us the mysteries of the Maya but also leave us thinking about our own past, present and future.