双手接胸部高度的球时，两眼要注视来球，两臂向前下方伸出迎球，五指自然分开。当手指触球后，两臂顺势将球引至胸前。
参考答案：错
The old man ____ for three years. [ ]
A. has died
B. has been died
C. has been dead
在一个端口从不转发状态进入转发状态之前，需要等待一个足够长的时间，这是为了解决在STP的端口状态变化过程中可能会出现的临时环路问题。
