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While some people believe the idea of alien invasion is the stuff of science fiction, others fear it may be just around the corner, after a number of UFO （unidentified flying object） sightings occurred in China last month.
Airline pilots and several witnesses reported seeing "a huge spherical illuminant" in the sky above Beijing and Shanghai on August 20, reported China Daily. Then on August 25, some strange objects were seen hovering above Xi’an for hours, according to a news program by Shaanxi Television.
《中国日报》报道称，在京沪两地，一些飞行员以及数位目击者都声称自己于8月20日这天在当地空中看到了一个“巨大球状发光体”。而稍后，陕西电视台的一档新闻节目报道称，8月25日，人们在西安上空发现一些神秘物体，它们悬浮空中长达数小时。
People have claimed UFO sightings around the world for centuries, and there are still more questions than answers.
几个世纪以来，世界各地不断有人宣称看到了不明飞行物，但结果得到更多的是疑问而非答案。
The United States is a particular center for alien spotting. Former American presidents Ronald Reagan and Jimmy Carter both reportedly saw UFOs.
美国格外受到外星人的青睐。美国前总统罗纳德？里根和吉米？卡特都曾公开表示亲眼看到过飞碟。
In 1952, the US Air Force began Project Blue Book, a study program on UFOs. However, in 1969 the government officially ended the program, stating that the incidents posed no threat and there was no evidence of space aliens.
1952年，美国空军开始着手实施“蓝皮书计划”，这是一项针对不明飞行物的研究项目。但是，1969年时，美国政府宣告终止该项目，声称这些事件不会构成威胁，且没有发现任何有关来自外太空的外星人的证据。
Private UFO research organizations have since taken on the task of providing the American public with the means to report UFO encounters.
从那时，一些私人性质的UFO研究组织开始继续该项工作，为美国民众提供上报UFO目击事件的途径。
Mutual UFO Network （MUFON） is one of the largest private UFO researchers in the US. According to Roger Marsh, director of communications for MUFON, the organization collected 14 UFO reports from New York in July.
联合UFO网络是美国最大的私人UFO研究机构之一。该机构的联络部主任罗杰？马什称，七月份，他们在纽约共收到了14份UFO目击报告。
However, with their shoestring budgets, these nongovernmental organizations can do little more than collect reports.
但是，由于预算十分紧张，这些非政府组织只能收集这些报告，除此之外什么也做不了。
In 2007, a panel of experts called on the US government to resume UFO investigations through the US Air Force or NASA.
2007年，有专家小组呼吁美国政府应责成美国空军或美国国家宇航局重启UFO调查行动。
The US Air Force, however, insisted: "Since the termination of Project Blue Book, nothing has occurred that would support a resumption of UFO investigations".
但美国空军方面却坚持认为：“自“蓝皮书计划”终止后，没有任何事件可以支持重启UFO调查行动。
The British government also tries to keep quiet UFO sightings because of "a lack of funds" to deal with them, said former Ministry of Defense UFO Project chief Nick Pope.
前英国国防部不明飞行物调查部门负责人尼克？蒲柏表示，英国政府也试图对UFO目击事件保持沉默，原因是“资金匮乏”。
"We were trying to do two things," he told the Huffington Post in August. "Either kill any media story on the subject, or if a media story ran, ensure that it ran in such a way that it would make the subject seem ridiculous and that it would make people who were interested in this seem ridiculous."
八月份，他在接受《赫芬顿邮报》记者采访时称：“我们一直尝试做两件事：一是消灭任何有关飞碟的报道，二是一旦飞碟事件报道传播开来，就试图让整个事件看起来荒诞离奇，让那些关注该事件的人们看上去十分荒唐可笑。
