单项选择题

Ringtones (手机铃音) are melodic (有旋律的) sounds a cell phone makes when an incoming call or message arrives. Since cellular phones are significantly more sophisticated than landline phones, ringtones can be (47) to suit the owner’s personal taste.
There are (48) two different types of ringtones: monophonic ringtones and polyphonic ringtones. Polyphonic ringtones are more musical than a monophonic ringtone. It is likely that future cellphones will be (49) of producing musical ringtones of CD quality. There are a number of websites that offer ringtones, pictures or even games to (50) . onto your cellphone. The websites vary in that some allow you to (51) specific ringtones while others offer subscriptions (订阅) that allow you to download an unlimited number of ringtones. When you (52) a ringtone, make sure that it will work with your cellular phone model and that the site is respectful of the artists’ copyright. Like any original works, artists receive payments for ringtones, so be sure that the website has the (53) to distribute the ringtone.
(54) , consumers will wish to compose personalized ringtones. Occasionally, cellphones can be programmed with ringtones by entering a series of buttons. Software is also (55) that allows consumers to create their own melodic ringtones. The software runs on a computer, and once the tune is perfected, it can be (56) to the phone via a data cable.

56（）

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