世界上第一台地动仪（候风地动仪）是我国（）发明。
A、司南
B、张衡
C、蔡伦
参考答案：B
通信网络和通信能力的增长是一定“增量”呈现()状递增的。
A.网
B.阶梯
C.棱形
D.圆柱
— ________ you interrupt now? Can't you see I'm on the phone?
— Sorry Sir, but it's urgent. [ ]
A. Can
B. Should
C. Must
D. Would
