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  3. Before the arrival of the internet, computer files were exchanged via storage media such as floppy disks (软盘) which were sent by

Before the arrival of the internet, computer files were exchanged via storage media such as floppy disks (软盘) which were sent by

admin2013-05-29  74
问题     Before the arrival of the internet, computer files were exchanged via storage media such as floppy disks (软盘) which were sent by post or delivered by foot, bike, car or train. After the appearance of the internet, a term was invented for such exchange of information: the sneakernet. Now that the internet is established, and our connections have become faster, the sneakernet sounds outmoded. Nevertheless, the opposite is true when larger files are considered. Because storage media evolve much faster than internet connections, it becomes ever more interesting to choose the route of physical transport over the internet.
    One of the routes is via carrier pigeon(信鸽). This may sound ridiculous (and it has been a popular joke for many years), but thanks to shrinking storage media, the speed and capacity of the pigeon internet promises to become quite amazing.
    A well trained contemporary carrier pigeon can maintain a speed of 50 kilometres an hour over a distance of 600 kilometres, and carry a weight of 1 gram. One gram does not seem to be much, but this weight can already contain quite some data. For instance, the Transcend Micro SD card weighing 1 gram has a capacity of 2 gigabytes.
    Compared to a fibre connection, the pigeon has to surrender quite fast. This internet connection only needs 2.6 minutes to send 2 gigabytes. A carrier pigeon only flies 2 kilometres far in that time. A carrier pigeon is thus faster than a fibre connection when the distance is shorter than 2 kilometres. A broadband connection needs 4 hours to send 2 gigabytes, while the pigeon can reach a distance of 200 kilometres in 4 hours. This means that sending 2 gigabytes of information from Amsterdam to Brussels goes faster by carrier pigeon than by a broadband connection. A dial-up connection needs 3.3 days to send 2 gigabytes, so in that case, the pigeon (flying 600 km per day) is faster than the internet up to a distance of about 2,000 kilometres.
    The bandwidth of a carrier pigeon increases faster than the bandwidth of the internet. Ten years in the future, a pigeon will be able to carry 2 terabytes (around 2,000 gigabytes). Our fibre connection will need 8.5 minutes for sending that amount of data. The carrier pigeon is then faster than a fibre connection if the distance is less than 7 kilometres-compared to 2 kilometres today.
For a distance of 500 km, the second fastest way of sending 2 gigabytes is by ______.
选项 A、dial-up connection
B、a carrier pigeon
C、fibre
D、broadband
答案D
解析
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