While troubleshooting a network connectivity problem, a technician observes steady link lights on both the workstation NIC and the switch port to which the workstation is connected. However, when the ping command is issued from the workstation, the output message "Request timed out." is displayed. At which layer of the OSI model does the problem most likely exist（）。

A.the session layer

B.the protocol layer

C.the data link layer

D.the access layer

E.the network layer

F.the application layer

The network administrator is asked to configure 113 point-to-point links.Which IP addressing scheme best defines the address range and subnet mask that meet the requirement and waste the fewest subnet and host addresses?（）

A.10.10.0.0/18 subnetted with mask 255.255.255.252

B.10.10.0.0/25 subnetted with mask 255.255.255.252

C.10.10.0.0/24 subnetted with mask 255.255.255.252

D.10.10.0.0/23 subnetted with mask 255.255.255.252

E.10.10.0.0/16 subnetted with mask 255.255.255.252

伯努利方程式中位置水头是相对基准面而言的，基准面()(A)必须是海平面

A.必须低于管线

B.只要是水平面就可以

C.只要是平面就可以

在全方位改革中，最核心和最重要的是什么？

利用产业引导扶持资金，按1万元带动1户(3人)的标准，经营主体5年内按“()”模式带动贫困户脱贫，并为贫困户提供就业岗位

A.返本还息

B.年终分红

C.按季结息

D.按月结息

镜泊湖位于黑龙江省宁安市西南的牡丹江上游，是中国最大的火山堰塞湖。（）