适合为保留器官，先化疗或放疗，后手术的是（）。 A.卵巢肿瘤 B.骨肉瘤 C.非霍奇

Sometimes drivers give him a tip, so that he has just enough money to _____.

A．live by

B．live for

C．live on

D．live with

“进出口货物征免税证明”的有效期为6个月，且实行“一批一证”的原则，即一份征免税证明上的货物只能在一个进口口岸一次性进口。( )

Frame Relay is simplified form of (25) , similar in principle to (26) , in which synchronous, frames of data are routed to different destinations depending on header information . Packets are routed throught one or more Virtual Circuits known as (27) . Most Virtual Circuits are (28) ,which means that the network provider sets up all DLCI connections at subscription time. (29) are also part of the Frame Relay specification . They privide a link that only lasts only as long as the session.

25（）

A．Datagram Switching

B．Datagram Routing

C．Packet Switching

D．packet Routing

关于“政府失灵”的叙述，正确的是（）

A.政府无法掌握正确决策所需的足够信息

B.“政府失灵”是由于市场经济负的外部性

C.政府在纠正经济不稳定方面完全无能为力

D.政府干预经济在创造财富的效率方面作用较大，但无法保证社会公平

烟雾病是一种慢性渐进性脑血管闭塞性疾病，伴脑底动脉异常增生，内科治疗效果欠佳，有各种手术方法，最常用且较为有效的是（）

A.血管重建（颅外-颅内血管搭桥）

B.颞肌直接贴敷于脑皮层表面

C.颞浅动脉直接放到脑皮层表面

D.大网膜移植

E.硬膜上动脉直接放到皮质表面