有利可图的意思是什么?

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Commercial (商业广告) business is profitable (有利可图的),and most radio and TV stations depend on the income. The prices for radio and TV commercials are different according to the popularity (声望) of the station and the time they give. Take WGY, a rock music station in Albary, New York, for instance, they ask $100 for a one-minute commercial from 6 a.m. to 10 a.m., the morning driving time. This is a time when people are driving on their way to work and they like to turn on their car-radios.
During other hours of the day the cost varies (变化) from $25 to $60 for one minute. TV commercials are much more expensive. During a good national or international football game or baseball game, the price for a one-minute TV commercial may reach as high as $100,000. On local TV station, prices of commercials are different according to the different programmes and the time of showing. At 7 p.m., when the TV stations are showing their most popular programmes, the price for a commercial for 30 seconds is $800.
49. This passage mainly tells that ________.
A. WGY, a rock music station earns much money by broadcasting commercials
B. the prices for commercials are different according to the different programmes
C. TV commercials are much more expensive than radio ones
D. commercial business can help most radio and TV stations earn a lot of money
50. The prices for radio and TV stations depend mainly on _______.
A. different radio and TV stations
B. different time the commercials are given
C. the most popular programmes
D. all of the above
51. How much does WGY, a rock music station ask for a half minute commercial at 9 a.m.?
A. $25 B. $50 C. $60 D. $100
52. When a commercial is shown at 7 a.m. on the local TV station for one minute, it will cost ________.
A. eight hundred dollars B. eighty hundred dollars
C. sixteen hundred dollars D. sixty hundred dollars