(B)

    In films, spies(间谍) are lucky people. They are smart and adventurous. But a real spy's life is not that exciting. They must live a life of lies. Their work is dangerous and they may have to pay for it with their lives. American spy Nathan Hale (1755-1776) was one of these people.

    Why does someone want to be a spy? Some do it for their country. Some for money. Some just love it. Nathan Hale became a spy for the first reason. He lived during the American Revolution (革命). He and his people fought the British army.

    In 1774, Hale joined the American army. Before that, he was a schoolteacher. Two years later, he chose to be a spy. He had to get information from the British army. He went to the city where the British army was staying. He told them that he was a schoolteacher and wanted to find a new job. He tried to get information for the American army. Hale finally got something important and decided to go back. He hid some papers in his boots. He went to the riverbank and waited for a boat to pick him up. However, British soldiers caught Hale at the riverbank and found the papers in his boots. It turned out(原来是) that as a young spy, Hale didn't have enough experience. He had told his secret to somebody else before. But that person sold him out to the British army. Hale died on Sept 22, 1776. His final words were: "It's a pity that I have but one life to lose for my country." He died at the age of 21.

    One of the most striking findings of a newly research in the UK is that of the people interviewed, one in two believes that it is becoming more difficult to meet someone to start a family with.

    Why are many finding it increasingly difficult to start close relationships? Does modem life really make it harder to fall in love? Or are we making it harder for ourselves? It is certainly the case today that contemporary couples benefit in different ways from relationships. Women no longer rely upon partners for money or status. A man doesn't expect his wife to be in (唯一的) charge of running his household and raising his children.

    But perhaps the knowledge that we can live perfectly well without a partnership means that it takes much more to persuade people to abandon their independence.

    In theory, finding a partner should be much simpler these days. Only a few generations ago, your choice of soul mate was limited by geography, social convention and family tradition. Although it was never clear，many marriages were essentially arranged. Now those barriers have been broken down. You can approach a builder or a brain surgeon in any bar in any city on any given evening. When the world is your oyster ( 牡蛎), you surely have a better chance of finding a pearl.

    But it seems that the old conventions have been replaced by the limitations of choice. The expectations of partners are raised to an unmanageable degree: good looks, impressive salary, kind to grandmother, and right socks. There is no room for error in the first impression.

    We think that a relationship can be perfect. If it isn't, it should be ended. We work to protect ourselves against future heartache and don't put in the hard emotional labor needed to build a strong relationship. Twelve-hour work at the office makes relaxed after-hours dating difficult. The cost of housing and child-raising creates pressure to have a stable income and Career before a life partnership.

某型号的电饭锅有两档，其原理如图所示，电阻R₁=44Ω，当开关S闭合时，电饭锅处于高温档，当开关S断开时，电饭锅处于焖饭、保温档，焖饭、保温时电饭锅的功率为高温档功率的0.02倍，求：