采集站由哪几部分组成？
参考答案：
采集站由前放、滤波、浮点放大、A/D转换、写寄存器、读寄存器、逻辑控制器、极性检测器以及转发器组成。
下列属于定性预测方法的是 ( )
A．简单平均法
B．历史类比法
C．因果分析法
D．加权平均法
—Could you tell me ____?
—It’s twenty minutes by underground.
A．how can I get to your school
B．how much it costs to get to your school
C．how far it is from your home to your school
D．how long does it take me to get to your school
