2 . Researchers at MIT and in China developed a simple, solar-powered water desalination (脱盐) system. They have made a breakthrough in getting fresh drinking water from sea water by using sunlight.

As the research paper published in Energy & Environmental Science explains, equipment applied in this system includes several layers of fiat evaporators (蒸发器) that turn water sources into fresh water through solar energy, as well as condensers (冷凝器) that cool the gas into the liquid. The authors of the paper are MIT students Lenan Zhang and Lin Zhao, Professor Evelyn Wang, and nine other researchers at MIT and at Shanghai Jiao Tong University in China.

How the system uses each of the multiple stages to remove salt from the water is critical to its efficiency. The heat released per stage will be used by the next stage. In this way, the team’s device can convert (转换) the energy of sunlight into the energy of water evaporation with an efficiency of 385 percent.

The device can be considered as a multilayer solar still. The heat is absorbed by its flat panels and then transferred to make water evaporate. The vapor then cools down and turns into liquid water on the next panel. As the water is collected, the released heat is transferred to the next layer.

The team’s 10-stage system produces pure water. Its quality is above the city drinking water standards. It also has the highest yield compared to other similar systems, at a rate of nearly six cubic decimeter per hour for every square meter of the solar collecting area. The system is distinguished from some others by the fact that there is no accumulated salt to be got rid of. Most materials of the demonstration unit don’t cost much and are easy to get.

Further experiments will be carried out on the device to optimize the choices of materials and test its durability under realistic conditions. Researchers will also work on the design of the device to make it more consumer-friendly. It is expected that the system could finally help developing regions that are short of electricity supplies but rich in sea water and sunlight handle water crises.

4 . Sitting back in my seat, I can’t quite believe that I’m about to travel along the railway that many foreign experts thought was “impossible”. All this time, the song “Sky Railway” has been ___________ inside my head. The words “railways like massive dragons are winding among the mountains” seem particularly _________ as I travel across the “roof of the world”.

I was one of the people who came from all parts of China to work on this railway._______   years to finish, the Qinghai-Tibet Railway is a record of all of our efforts to _______ the most difficult engineering challenges. How to _______ the delicate ecosystem (脆弱的生态) was the most important.

The first landmark to catch my eye is the splendid Qingshuihe Bridge, the world’s longest bridge built over permafrost. Look! A group of Tibetan antelopes is moving _______ the bridge, with some stopping to eat grass at their _________. Thirty-three passages(通道) have been built under the railway to allow the animals to move safely and freely in their natural _______. Wild animals such as these Tibetan antelopes have now been using these _______ for years. They seem totally __________ that we are speeding past at over 100 kilometers an hour.

To prevent ________ to wetlands and grasslands, 675 bridges with ________ about 160 kilometer were built between Golmud and-Lhasa.

The journey has been flying by, and before I know it, we have reached Tanggula Station.________at over 5,000 metres above sea level, this is the ________ railway station in the world. In locations such as this, the thin air,________weather and high levels of UV radiation presented perhaps the greatest ________ for railway workers. To make sure we stayed ________, several oxygen-making stations were built. We were also able to enjoy ________ breaks in lower areas.

As we pass Cuona Lake, I feel a sense of pride and achievement. It is so close to the railway that I want to ________ and touch its pale blue mirror-like surface. I am proud that we built our “impossible” railway, and did so with the ________ that the environment deserves. It truly is an extraordinary “Sky Railway”.

10 . Dozens of dolphins swam out of the polluted waters of Haifa Harbor on Tuesday. This was the first time that dolphins had visited this crowded Mediterranean Port, and researchers were surprised by the unexpected event.

Between 40 and 50 of the dolphins appeared in the busy port on Tuesday morning, obviously drawn by the fish-rich waters of Haifa Bay.

However, the bay is also full of harmful chemicals. Avia d Sheinin, professor of Haifa University’s Maritime Studies Department, said he didn’t think the dolphins were harmed by the pollution, but that he hoped they would swim back to the sea soon. “It seems that they are quite relaxed. They don’t seem to be stressed,” he said.

Haifa Bay is lined by chemical companies that have been pouring poisonous waste into the water for decades. While pollution levels have dropped in recent years, the water is still considered a health hazard, whispering warnings to those who draw near.

“There are lots of fishes in Haifa Port. Unfortunately, we couldn’t tell the dolphins that the fish are not healthy, and I don’t know what the result will be,” he told Israel Army Radio.

Hundreds of Haifa residents gathered around Haifa Bay to see the interesting sight, and researchers said this provided a rare chance to film and study the rough-toothed dolphins. In addition to the dozens of dolphins which swam into the port on Tuesday, a similar number stayed outside the breakwater (防波堤). Later Tuesday the dolphins left the port but remained near the entrance and Israel’s coastguard was patrolling (巡逻) the area to try to make sure the dolphins didn’t re-enter the poisonous waters.

Relatively little is known about rough-toothed dolphins, which are usually found in deep and warm tropical waters.