2008 Shandong Question 63 Single-choice Differentiating 2008_山东卷 (英语) 63. The carriers’ $participation in the system is determined by _______.$ A. the US federal governmentB. mobile phone usersC. the carriers themselvesD. the law of the United States Answer keyC ☆ SaveCan't do it, show the explanation查看原卷 →