IP multicasting is a set of technologies that enable efficient delivery of data to many locations on a network. Rather than making multiple copies of a message intended to be distributed to multiple recipients at the (71) of origin of a message, multicasting initially sends just one (72) and does not copy it to the individual recipients until it reaches the closest common point on the network, thereby (73) the bandwidth consumed. Network performance is significantly (74) because it isn’t bogged down with the processing and transmission of several large data fries; each receiving computer doesn’t have to (75) the transmitting server for the file.

A．point

B．bottom

C．head

D．sight

宫外孕破裂患者，血压70/30mmHg，脉搏125次/分，面色苍白，需急诊手术。

应选择哪种麻醉方法（）

A.腰麻

B.静吸复合全麻

C.硬膜外麻醉

D.硬膜外-腰麻联合麻醉

E.骶管阻滞