"This is a really exciting time—a new era is starting," says Peter Bazalgette, the chief creative officer of Endemol, the television company behind "Big Brother" and other popular shows. He is referring to the upsurge of interest in mobile television, a nascent industry at the intersection of telecoms and media which offers new opportunities to device-makers, content producers and mobile- network operators. And he is far from alone in his enthusiasm.
Already, many mobile operators offer a selection of television channels or individual shows, which are " streamed" across their third-generation (3G) networks. In South Korea, television is also sent to mobile phones via satellite and terrestrial broadcast networks, which is far more efficient than sending video across mobile networks; similar broadcasts will begin in Japan in April. In Europe, the Italian arm of 3, a mobile operator, recently acquired Canale 7, a television channel, with a view to launching mobile-TV broadcasts in Italy in the second half of 2006. Similar mobile-TV networks will also be built in Finland and America, and are being tested in many other countries.
Meanwhile, Apple Computer, which launched a video-capable version of its iPod portable music-player in October, is striking deals with television networks to expand the range of shows that can be purchased for viewing on the device, including "Lost", "Desperate Housewives" and "Law & Order". TiVo, maker of the pioneering personal video recorder (PVR), says it plans to enable subscribers to download recorded shows on to iPods and other portable devices for viewing on the move. And mobile TV was one of the big trends at the world’s largest technology fair, the Consumer Electronics Show, which took place in Las Vegas this week.
Despite all this activity, however, the prospects for mobile TV are unclear. For a start, nobody really knows if consumers will pay for it, though surveys suggest they like the idea. Informa, a consultancy, says there will be 125 million mobile-TV users by 2010. But many other mobile technologies inspired high hopes and then failed to live up to expectations. And even if people do want TV on the move, there is further uncertainty in three areas: technology, business models and the content itself.
It can be inferred from the last paragraph of the text that（）
A. mobile TV is coming—but how the market will develop is still unclear
B. consumers favor mobile TV if they need not pay for it
C. few mobile technologies failed to live up to expectations
D. the three uncertainties referred to at the end of the text are hopefully overcome in no time
的物块，始终固定在倾角为
的斜面上，下面说法中正确的是（ ）
，斜面对物块没有做功
移动距离
，方向竖直向上，位移方向也向上，所以
，故②正确.③物块和斜面一起向左以加速度
移动距离
，物块所受的合力做的功等于
，物块受到重力和斜面对物块的力，因重力做功为零，所以斜面对物块做的功等于
，所以斜面对物块做的功等于
，故④错误．综上①②③正确，故选A．