专业四级是针对英语专业同学的重要考试，其真题的参考价值无可比拟，希望同学们能够吃透真题，通过专四。
Hints:
AT&T
U.S.
iPhone
Internet
AT&T plans to spend $18 billion in 2010 upgrading its wireless networks to handle the increasing amount of new traffic. This is roughly $2 billion more than the company had invested in the previous year. Specifically, AT&T will add 2,000 new cell sites and upgrade existing cell sites with three times more fiber links than it had in 2009. This will increase capacity to connect the cell towers to AT&T's main network. AT&T, which is the only wireless operator in the U.S. selling the iPhone, has been the target of much criticism over this past year, as many iPhone subscribers, particularly in densely populated urban areas, have complained about dropped calls, slow Internet access, and poor service. Some critics claim the company has not been spending enough on network upgrades to keep up with growing demand. AT&T has acknowledged that it has faced some difficulties, particularly in big cities. But the company is "closing the gap."