移动业务区
参考答案：能够进行蜂窝通信服务所覆盖的基本区域，一般是指提供蜂窝电话服务的蜂窝状业务区域。
I don't think he could have finished his work last night, ________? [ ]
A. do I
B. did he
C. has he
D. could he
（４分）有下边各组物质，请按要求填入序号：
①__ 组两物质互为同位素。
② __组两物质互为同素异形体。
③ __组两物质互为同分异构体。
④ __组中的物质是同一物质。
