6502电气集中记录电路由哪些继电器组成，作用是什么？
参考答案：
记录电路主要有按钮继电器和方向继电器电路组成，用于记录行车指令、区分进路的性质和方向。
与温里药"助阳气"功效有关的药理作用是（）
A.镇痛
B.抗心律失常
C.平喘
D.抗炎
E.强心、扩张血管、增加血流量
Spread spectrum simply means that data is sent in small pieces Over a number of the (46) frequencies available for use at any time in the specified range. Devices using (47) spread spectrum (DSSS) communicate by (48) each byte of data into several parts and sending them concurrently on different (49) . DSSS uses a lot of the available (50) , about 22 megahertz (MHz) .
（49）是（）
A.bits
B.frequencies
C.packets
D.messages
