One spring morning many years ago, I had been prospecting for gold along Coho Creek in southeastern Alaska. Suddenly, no more than 20 paces away was a huge Alaskan timber wolf-caught in a trap.

From her appearance, I guessed she had been trapped for several days. She needed my help, I thought. But if I tried to release her, she would turn aggressive to me. The wolf was clearly suffering. The trap's steel jaws had imprisoned two toes. They were swollen and lacerated, but she wouldn't lose the paw (爪子) — if freed. Yet each time I moved closer, she would make a frightening growl. If I could only win her confidence, I thought. It was her only hope.

Over the next few days, I divided my time between prospecting and trying to win the wolf's trust. I talked gently with her, throwing her some meat. Gradually, I kept edging closer — though I was careful to remain beyond the length of her trap chain.

At dusk on the fifth day, I delivered her dinner. Suddenly, I saw a slight wagging of her tail. I moved within the length of her chain. She remained sill. As a towering man, my heart was in my mouth, though. Within her reach, I wrapped my blanket around myself and slowly settled onto the cold ground. It was long before I fell asleep.

The next morning, I slowly placed my hand on the wolf's injured leg. Unexpectedly; she made no threatening move. Then I applied pressure, the trap sprang open, and the wolf pulled free.

My experience told me the wolf would vanish into the woods quickly. But cautiously, she crept toward me and sniffed my hands and arms. This went against everything I'd ever heard about timber wolves. Yet, strangely, it all seemed so natural.

Why do we like drinking water from plastic bottles（塑料瓶）? Some people think it is healthy and clean. Others drink bottled water because it’s easy — you can carry it around with you. In hot countries, like Greece, we often buy bottles of cold water in the summer.

However, making lots of plastic is not a good idea for many reasons. First of all, we need a lot of oil for plastic products. We usually use oil as a source of energy. If we reduced the number of bottles we made, we wouldn’t need so much oil. Plastic bottles also pollute the environment. If we reused all our plastic bottles, we wouldn’t need so much space for rubbish dumps. But in Greece, we don’t reuse much of the plastic we use. In 2006, Greeks reused only about 10% of plastic waste. The rest became rubbish on land and in rivers and seas.

So next time you want to throw away a plastic bottle in the litter bin, stop and think. If you reuse it, you would help the environment. But what can you do when there isn’t a bin near you? Well, there are lots of useful ways that you can use your bottles again. For example, an empty bottle makes a great piggy bank for your pocket money, and if you cut a bottle in half, you will have a plant pot. Go green! You can make a difference.

A culture guide named Persephone welcomes travellers to Greece and takes them through a famous cave in the north. The guide moves smoothly around the underground area and can talk about it in 33 languages. It can also answer 33 questions, but only in the Greek language.

Persephone is intelligent and it is a human-sized robot. The robot has been in operation for about a month at the Alistrati Cave. Persephone guides visitors through the first 150 metres of the cave that is open to the public. For the remaining 750 metres, a human guide takes over.

The idea of creating the robot guide was put forward by Nikos Kartalis, who is the scientific director at the Alistrati site. He had this idea when he saw one on television guiding visitors at an art show. Persephone was built by the National Technology and Research Foundation and cost about 139,000 dollars. “People who had visited in the past are coming back to see the robot guide,” said Nikos. “Many foreign visitors couldn’t believe Greece had the ability to build a robot and use it as a guide in the cave.”

The robot, with a white body, black head, and two bright eyes, moves on wheels. It guides visitors to the first three of eight stops along the walkway. It can do two more stops, but it is too slow for the tour. Persephone’s creators are considering ways to increase her speed. The robot begins the tour by saying, “My name is Persephone. I welcome you to the Alistrati Cave. ”

Evdokia Karafera is a human guide who partners with Persephone. “It is helpful, because it speaks many languages,” she said. “There’s just a little delay in the touring. Most find it fascinating, especially the children, and find it interesting that it speaks many languages. Robots, at some point in the future, will take over many jobs. But I believe they cannot take the place of humans everywhere.”