Bottled water has become the choice for people who are healthy and thirsty. Bottled water is all over the world. But some say the planet's health, and people's health may be suffering from it.

    The idea that bottled water is safer for humans may not be true. The Natural Resources Defense Council of America said, “There is no promise that because water comes out of a bottle, it is cleaner or safer than water from the tap.” Another New York City-based action group added that some bottled water is “really just tap water in a bottle—sometimes more clean, sometimes not.”

    It is not proven that bottled water is better than tap water. Nick Reeves from the Chartered Institution of Water and Environmental Management said, “The high mineral content(含量) of some bottled water makes them not good for feeding babies and young children.” Also, most bottled water doesn't have fluoride(氟化物), which can make teeth stronger. Kids are drinking more bottled water and less fluoridated tap water, and some say that's behind the recent rise in bad teeth.

    Storing is another problem. Placed near heat, the plastic bottles can produce bad chemicals(化学物质) into the water.

    According to the Environmental Protection Agency, some 2.7 million tons of plastic are used worldwide to bottle water each year. The plastic can take between 400 and 1,000 years to break down.

    In terms of energy use, plastic bottles are also not cheap. One report said that if water and soft drink bottlers had used 10 percent recycled materials in their plastic bottles, they would have saved about 72 million gallons of gas.

    So, if you are worried about the effect of bottled water on the Earth, you can take the following steps.

●Drink from your tap. Unless your government warns against this, it should be fine.

●Get a container(容器). Carry your tap water in a steel or a lined drinking container, and clean it between uses.

●Keep it cool. Don't drink from a bottle that has been sitting in the sun, don't store it near chemicals, and don't reuse plastic bottles.

●Choose glass containers over plastic if possible. When finished, recycle!

    “Hello, Earth! Can you hear me?” That's voice more than 400,000 people received recently. It was from Philae, a space vehicle that landed on a comet(彗星)in 2014. However, its transmissions (传输信号)back home went silent since then.

It took a long time for Philae to make its way across the solar system (太阳系)and reach comet 67P/C-G. The pace vehicle got there aboard the Rosetta probe (探测器), which has been circling around the comet since Philae separated from it in November, 2014．

Philae's job was to collect materials to study the comet's composition. And for about two and a half days after landing, it did just that, sending the information back to scientists on Earth. But Philae's landing on the comet's icy surface had not been smooth. While touching down, it jumped up and ended up in the shadow of something like a huge rock. Philae runs on solar power, but there was no light in the place where it landed. In the end, it failed to work.

However，as comet 67P/C-G moved closer to the sun, more sunlight reached the space vehicle, allowing it to power up and come back online. Philae then sent something to Rosetta, which passed on the information back to Earth.

“We only received the information for about 85 seconds, but that's enough to let us know it is alive and well,”says Stephan Ulamec, who works for the European Space Agency.“We hope to work out where it landed exactly on the 4-kilometer-wide comet. Now we plan to change how Rosetta moves so that Philae can keep on communicating and receiving instructions.”

    Dujiangyan is the oldest man­made water system in the world, and a wonder in the development of Chinese science. Built over 2, 200 years ago in what is now Sichuan Province in Southwest China, this amazing engineering achievement is still used today to irrigate over 6, 000 square kilometers of farmland, take away floodwater and provide water for 50 cities in the province.

    In ancient times, the region in which Dujiangyan now stands suffered from regular floods caused by overflow from the Minjiang River. To help the victims of the flooding, Li Bing, the region's governor, together with his son, decided to find a solution. They studied the problem and discovered that the river most often overflowed when winter snow at the top of the nearby Mount Yulei began to melt as the weather warmed.

    The simplest fix was to build a dam, but this would have ruined the Minjiang River. So instead Li designed a series of channels built at different levels along Mount Yulei that would take away the floodwater while leaving the river flowing naturally. Better still, the extra water could be directed to the dry Chengdu Plain, making it suitable for farming.

    Cutting the channels through the hard rock of Mount Yulei was a remarkable accomplishment as it was done long before the invention of gunpowder and explosives. Li Bing found another solution. He used a combination of fire and water to heat and cool the rocks until they cracked and could be removed. After eight years of work, the 20­metre­wide canals had been carved through the mountain.

    Once the system was finished, no more floods occurred and the people were able to live peacefully and affluently. Today, Dujiangyan is admired by scientists from around the world because of one feature. Unlike modern dams where the water is blocked with a huge wall, Dujiangyan still lets water flow through the Minjiang River naturally, enabling ecosystems and fish populations to exist in harmony.

    Forty-three years ago, a man took a "small step" on the moon and brought mankind a "giant leap" forward. As the first person to walk on the moon, American astronaut Neil Armstrong is a man whose name will be remembered for generations to come.

    But being the first is never easy. With so many unknowns about space at that time, Armstrong himself was astonished that Apollo 11 actually worked. He thought he and his partners had merely a 50 percent chance of a successful landing back in 1969.

    It was tough indeed. When the module (登月舱) was approaching the moon's surface, the computer wanted to rest them on a steep slope covered with rocks, but Armstrong realized it was an unsafe place to stop.

    As a last minute decision, he safely landed the module by himself. When they finally touched the ground, "there was something like 20 seconds of fuel left," he said in an interview earlier this year.

    Unfortunately, some people doubted his visit to the moon, saying it was faked. But Armstrong responded with a chuckle (轻声笑), saying: "It was never a concern to me because I knew one day, somebody was going to go fly back up there and pick up that camera I left."

    For all his global fame, Neil Armstrong is a remarkably modest man. He rarely gave interviews and didn't like talking about his achievement. He stopped giving his signatures when he found that people sold them for thousands of dollars.

    "I guess we all like to be recognized not for one piece of fireworks but for the ledger (记账簿) of our daily work," Armstrong said in a CBS interview in 2005. When asked how he felt knowing his footprints would be likely to stay on the moon's surface for thousands of years, he said: "I kind of hope that somebody goes up there one of these days and cleans them up."

    Armstrong passed away last month at the age of 82, but he will be memorized. "The next time you walk outside on a clear night and see the moon smiling down at you, think of Neil Armstrong and give him a wink (眨眼示意)," his family said to Reuters.

    When a laptop or smartphone battery starts losing its power, the only options are to buy an expensive replacement, or just keep it plugged in all the time. But a woman Mya Le Thai may have found the answer to this problem.

    Thai was frustrated that the batteries for her wireless devices degraded(降级)over time, until they failed to charge fully. She did not like having to keep her laptop connected to an electrical outlet to keep it powered on. So, she decided to do something about that problem. At first, she and her team at UC Irvine thought about inventing a new battery. But as they experimented, Thai discovered something that might permit lithium—ion(锂离子)batteries to last forever.

    Lithium-ion batteries power most wireless devices. Over time, the batteries lose the ability to hold a charge. Most of these batteries have a life span of about 7,000 charging cycles before they die. One of the reasons lithium—ion batteries degrade is their use of nanowires to carry electricity. Nanowires are extremely thin. A human hair is thousands of times thicker, for example. Nanowires are extremely efficient carriers of electricity, which makes them useful in batteries.

    But, Thai had a theory—the nanowires might last longer if covered with a gel(凝胶). She and her team tested this theory. "It was a long process and a lot of work, "Thai said. The team tried many coverings for the wires. PMMA, a type of plastic, was one of them. The nanowires were coated with PMMA and cycled through charges 200, 000 times. The PMMA-coated nanowires showed no evidence of damage. The results suggest that batteries could last forever, without losing charging ability.

    Thai hopes to continue her research to understand why this gel works so well and to see if any other gel could create better results and she is enjoying the publicity about her discovery. She said she never expected her research to get media coverage. "It's kind of cool," she said. "I'm really glad people are showing interest in my work and not just in the work itself, but also in technology and energy."

When it comes to having fun in the sun, it's easy to lose track of time. If you're not careful, this can be quite dangerous.{#blank#}1{#/blank#}But it can easily be prevented—all you need is a little sunscreen.

{#blank#}2{#/blank#}People have been using chemical pastes to protect themselves from the sun for centuries. But the first modern sunscreen sold on the market was offered by French company: L'oreal in 1935.

Several other companies were quick to release their own sunscreens. Perhaps the biggest advancement in the world of sunscreen came in the 1970s, when scientists started looking at the sun protection factor, or SPF.{#blank#}3{#/blank#}

The advantages of using sunscreen are obvious. It limits the painful effects of sunburn.{#blank#}4{#/blank#}Millions of people have died from skin cancer caused by ultraviolet rays from the SUITL. Remember to apply sunscreen 30 minutes before going outside.

Unfortunately, there are many mistaken ideas about sunscreen.{#blank#}5{#/blank#}Some also think you only need to put it on once for a whole day's protection or that you don't need it on cloudy days. None of these things are true. Experts say you should apply sunscreen every two hours when outside in the daytime, no matter how dark your skin is or what the weather is like.

A. And it can even save your life.

B. Sunscreen is not exactly a recent invention.

C. Choosing a sunscreen isn't as simple as it used to be.

D. In direct sunlight, sunburn can occur in less than 15 minutes.

E. This rating is a number that shows how effective a sunscreen is.

F. It's believed that you don't need much sunscreen if you have dark skin.

G. Some think a good method is to cover as much as possible with protective clothing.