某电脑软件公司共有员工40人，其中包括4名管理人员，23名销售人员，8名专业人员，5

“测土配方施肥”技术就是农技员对某土地检测后给出施肥配方，配方中主要有KNO₃、K₂SO₄、NH₄NO₃、NH₄H₂PO₄等物质．请回答下列问题：

（1）上述物质中属于复合肥的是______（写一种即可）．

（2）取少量配方中的物质溶解于水，所得溶液的PH=6.2，则该溶液显______性．

（3）NH₄NO₃和NH₄H₂P₄不能与碱性肥料混合施用，原因是______．

（16分）如图所示，两水平线L₁和L₂分别是水平向里的匀强磁场的边界，磁场的磁感应强度为B，宽度为d，正方形线框abcd由均匀材料制成，其边长为L（L<d）、质量为m、总电阻为R．将线框在磁场上方高h处由静止开始释放，已知线框的ab边刚进入磁场时和刚穿出磁场时的速度相同．求：

（1）ab边刚进入磁场时ab两端的电势差U_ab；

（2）ab边刚进入磁场时线框加速度的大小和方向；

（3）整个线框进入磁场过程所需的时间．

The metric assigned to each network depends on the type of protocol. Some simple protocol, like RIP, treats each network as equals. The ___44___ of passing through each network is the same; it is one ___45___ count. So if a packet passes through 10 network to reach the destination, the total cost is 10 hop counts. Other protocols, such as OSPF, allow the administrator to assign a cost for passing through a network based on the type of service required.A ___46___ through a network can have different costs (metrics). For example, if maximum ___47___ is the desired type of service, a satellite link has a lower metric than a fiber-optic line. On the other hand, if minimum ___48___ is the desired type of service, a fiber-optic line has a lower metric than a satellite line. OSPF allow each router to have several routing table based on the required type of service.

46（）

A．adaptability

B．scalablity

C．route

D．security

为什么家用电器的插头和插座大多采用三线的？

个人缴费年限累计满（）年的退休后按月发给基本养老金。