4G主套餐包括（）套手机套餐和1套4G无线宽带套餐（数据类终端专用）。
A.1
B.2
C.3
D.4
参考答案：C
He is said___________a book on the history of Chinese tone bridge , but I don’t know if he has finished it.
A. to have written B. to be writing C . having writing D writing
如图所示，电路中电键S闭合时，电表V1、V2、A的示数分别为220V、110V、0.2A．某时电路出现故障，V1和V2的示数都变为220V，而A的示数变为零时，则（ ）
A．出故障的是L1，且L1断路
B．出故障的是L2，且L2断路
C．出故障的是L1，且L1短路
D．L1和L2都同时断路
I don’t know if he has finished it.