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在信用卡时代，货币已变成塑料制品，而实际上现金也正在越来越多的国家变成塑料制品。传统的纸币流通了300多年之后正在逐渐被新的聚合物工艺制造的货币所取代。 塑料钞票的优点是相当值得考虑的。它比纸币成本大约高1倍，却有4到5倍的使用寿命——澳大利亚的10澳元纸币平均寿命为8个月，而塑料钞票至少能用30个月。塑料钞票还能使自动取款机的卡纸现象减少38%。
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Passage One For more than thirty years after astronauts first set foot on the Moon, scientists have been unable to unravel the mystery of where the Earth’s only satellite came from. But now there is direct evidence that the Moon was born after a giant collision between the young Earth and another planet. Previous studies of rocks from the Earth and the Moon have been unable to distinguish between the two, suggesting that they formed from the same material. But this still left room for a number of theories explaining how—for example, that the Moon and Earth formed from the same material at the same time. It was even suggested that the early Earth spun so fast it formed a bulge that eventually broke off to form the Moon. Franck Poitrasson, and his colleagues at the Swiss Federal Institute of Technology have compared Moon rocks with rocks from Earth and discovered a surprising difference. They analysed the weight of the elements present in the rock using a highly accurate form of mass spectroscopy(光谱研究) that involves vaporising a sample by passing it through an argon (氩) flame. Although they appeared very similar in most respects, the Moon rocks had a higher ratio of iron-57 to iron-54 isotopes(同位素)than the Earth rocks. "The only way we could explain this difference is that the Moon and the Earth were partly vaporised during their formation," says Poitrasson. Only the popular "giant planetary impact" theory could generate the temperatures of more than 1700℃ needed to vaporise iron. In this scenario, a Mars-sized planet known as Theia crashed into Earth 50 million years after the birth of the Solar System. This catastrophic collision would have released 100 million times more energy than the impact believed to have wiped out the dinosaurs—enough to melt and vaporise a large portion of the Earth and completely destroy Theia. The debris from the collision would have been thrown into orbit around the Earth and eventually coalesced to form the Moon. When iron is vaporised, the lighter isotopes burn off first. And since the ejected debris that became the Moon would have been more thoroughly vaporised, it would have lost a greater proportion of its lighter iron isotopes than Earth did. This would explain the different ratios that Poitrasson has found. The main theme of the passage is ______.
考虑一元二次方程x2+Bx+C=0，其中B，C分别是将一枚骰子接连掷两次先后出现的点数．求该方程有实根的概率p和有重根的概率q．
某公司设置VPN服务器允许外地的公司员工通过Internet连接到公司内部网络。 【问题3】 VPN路由器配置如下：请解释画线部分含义： Vpdn-group 1 (1) Accept-dialin protocol l2tp virtual-template 1 terminate-from hostname a801 (2) Local name keith Lcp renegotiation always (3) No 12tp tunnel authentication
Passage Five I’d been living with my wife for eight years and one night. Morn says, "I guess you guys are never going to get married. I mean, you’ve been through jail together, you’re living together, but…, oh, forget it." "Oh, well," I said," put it like that and I’ll marry your daughter tomorrow." Actually, I don’t know what we were waiting for, except that for a guy it’s never the right time to get married. I’ m also suspicious of any two people who don’t struggle with that decision. Part of my problem was that I was still lusting in my heart after other ladies. But somehow I knew that I wasn’t going to find another woman remotely as great as my soon-to-be wife. It’s a good thing my mother-in-law finally spoke up. I finally gathered my courage one day when we were having a picnic, and popped the question. I also gave my wife a big tourist pamphlet about Switzerland. I wasn’t taking any chances. She said no. It killed me. I felt sick to my stomach. I lost my appetite. Our dog just stared at me, thinking, "If you’re not going to eat your lunch, I will." Finally, I said, "But the Switzerland trip is yours if you say yes." "Switzerland , "she said, "is filled with precise, humorless people." "Maybe I should have suggested Paris" For a minute it seemed as if my change in travel plans would rate a solid "maybe". But she said no again. When we woke up the next morning, she told me that she’d slept on my proposal. "I guess I was a little rude to you last night," she explained. Meanwhile, I’m figuring I’m off the hook for this marriage thing for at least another eight years. I could afford to be generous. "I asked, you said no. It’s okay," I said. I might have looked a little too relieved because later that day she gave me a little box. Inside was a gold watch. On the back was inscribed. "Yes. I’ve reconsidered." I liked the watch, so I did the right thing. The last sentence "I did the right thing" implied he ______.
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