我国的《公路沥青路面再生技术规范》建议水泥等活性填料一般不超过（）
A.1%
B.1.5%
C.2%
D.2.5%
参考答案：B
The Smiths moved to China ten years ago and here since then. [ ]
A. has lived
B. was living
C．live
D. have lived
恒压供水系统的PID调节器的作用是把压力设定信号和压力反馈信号经运算后，输给变频器一个（）控制信号。
A.温度
B.频率
C.电阻
D.热量
