利用流体流动时静压能与动压能相互转换的原理来吸送流体的泵是（）。
A．水环泵
B．水锤泵
C．喷射泵
D．电磁泵
参考答案：C
不宜急于手术治疗的甲状腺肿是（）
A.颈部压迫症状
B.继发甲亢
C.结节性甲状腺肿
D.胸骨后甲状腺肿
E.可疑恶变
When a bridge transmits an Ethernet frame, the Ethernet frame has （）.
A．the broadcast address for the its source address
B．the bridge's LAN address for its destination address
C．the bridge's LAN address for its source address
D．none of the above
