The social network Facebook says it's planned to use solar powered drones to provide internet access to millions of people in the developing world. The first of the devices built by a team in southwest England has successfully taken to the skies in the United States. Facebook hopes that the drones will eventually be able to stay in the air for months and deliver internet to villages in Africa and India using invisible lasers. Here is our technology correspondent Rory Cellan-Jones.
Two years ago, Facebook bought a centre, a small firm which specialized in making drones. Its plan was to use it in an ambitious project to connect remote places in Africa and elsewhere to the Internet. A team in Bridgewater has now built a solar powered aircraft with a wingspan of a Boeing 737 but weighing a third as much as a car. Now the social network has reviewed that the first flight with the unmanned plane has taken place in Arizona. It was airborne for 90 minutes. But Andy Cox the British engineer running the project says that is just a start.
Facebook plans to build a fleet of these drones which will beam an internet signal to people within a sixty-mile diameter. But it will be some years before the drones are ready to go into service. And in the meantime, other technology firms, notably Google are attempting something similar.
It was twenty years ago that Dolly the sheep became the first mammal ever to be cloned from the cell of an adult animal. Dolly died young at the age of six. But research on cloning techniques is continuing and Dolly has sisters for identical sheep all cloned from the same adult.
Scientists want to know whether they like Dolly are going to die young and if they age in a normal way.
I'm feeling the joints for any kind of heat or swelling. And then we can pick up the leg and gently manipulate them to check that they flex and extend as normal. Veterinary surgeon puts Daisy the sheep through a very hands-on physical examination.
You can see she is not really bothered by that at all.
But Daisy is not just any sheep. She is a clone, one of her flock of thirteen clone sheep currently living out their lives on a farm owned by the University of Nottingham. And one of only four, the others are Debby, Denis and Dian cloned from the same adult is Dolly the sheep, the first clone mammal born in 1996, which despite the passage of a couple of generations in sheep years makes them Dolly's identical twins sisters.
1.Social network 社交网络
例：Many companies have employed social network applications to improve productivity by processing and sharing people's information.
2.Take to the sky 冲上云霄，飞向高空
例：When Hiccup and Toothless take to the sky, we're free of constraint, aware of the space on all sides.
3.Specialize in 专门研究，专门经营
例：Many students specialize in engineering.
注：可与"happen","occur", "come off"等词或词组替换 。
例：When does the wedding take place?
5.Physical examination 体格检查
例：I was accompanied by my mother to the hospital for a physical examination.
两年前，Facebook购买了一个中心--一家专门经营无人机制造的小公司，计划利用它实现一项雄心勃勃的工程，即让非洲等地的偏远区域连上互联网 。目前，布里奇沃特的一个团队已经制造出了一架太阳能飞机，该飞机拥有波音737的翼展，但重量相当于三辆汽车 。如今，该社交网络评估得出，无人机已在美国亚利桑那州进行首飞，飞行时长90分钟 。但经营该项目的英国工程师安迪·考克斯说，这只是个开始 。
Facebook计划制造无人机组，向直径60英里以内的人发送互联网信号，但无人机提供此项服务还需要几年的时间 。同时，其他科技公司，尤其是谷歌正在尝试类似的技术 。
我在触摸她们的关节，看有没有发热或肿胀 。然后我们可以抬起她们的腿，轻轻摆动看是否能够正常伸缩 。兽医正在亲手对黛西进行体检 。
而黛西绝不是一只普通的羊，她是克隆羊，是13只克隆羊中的一只，现在生活在诺丁汉大学的农场上 。而第一只克隆哺乳动物、出生于1996年的多莉是从同一成年动物克隆出来的四只羊中的一只，其他三只分别叫黛比、丹尼斯和戴安 。尽管羊群经过了几次新老更迭，但她们还是多莉的同卵双胞胎姐妹 。