与根面龋有关的是（） A.变形链球菌 B.乳杆菌 C.放线菌 D.产黑色普氏菌 E.

In low-speed network, it is usually adequate to wait for congestion to occur and then react to it by telling the source of packets to slow down. In high-speed networks, this approach often works poorly, because in the (71) between sending the notification and notification arriving at the source thousands of additional (72) may arrive．InATMnetwork，amajortoolfor preventing (73) is (74) control. When ahostwants a new virtual (75) , it must describe the traffic to be offered and the service expected.

A．flow

B．admission

C．traffic

D．time

用化学用语表示：

（1）硝酸铜______； 

（2）3个甲烷分子______；

（3）一根生锈的铁钉在稀硫酸中浸泡一会后，可发现铁锈会逐渐溶解，溶液慢慢变为黄色，请写出能反映该过程的化学方程式______；

（4）硫酸的电离方程式______．

IP地址按照其逻辑层次可分为( )类。

A．2

B．3

C．4

D．5

含有一个结晶水时为白色结晶，失去结晶水即液化的是（）

A.卡莫司汀

B.环磷酰胺

C.氟尿嘧啶

D.塞替派

E.巯嘌呤

复励发电机因为有串激绕组，可以自动调节电压，因而外特性（）

A.较为平稳

B.起初电压增长较快

C.电流增大到临界值后反而减小

D.稳定短路电流较小