2013年12月四级词汇理解

2013年 12月四级 The mobile phone is a magic device widely used these days. Although it has been nearly 30 years since the first commercial mobile-phone network was launched, advertisers have yet to figure out how to get their  36  out to mobile-phone users in a big way. There are 2.2 billion cell-phone users worldwide, a  37  that is growing by about 25% each year. Yet spending on ads carried over cell-phone networks last year  38  to just $ 1.5 billion worldwide, a fraction of the $ 424 billion glo