各类武器装备和物质应当严格登记手续，按照“三分四定”的要求，分类摆放整齐。其中“三分

试述煤中灰分增大对输煤系统有何影响？

肾脏由几部分结构构成：①肾实质、肾窦②肾皮质、肾髓质③肾锥体、肾柱、肾 * * ④肾盏、肾盂、肾动脉、肾静脉、脂肪

A．①

B．①②

C．①②③

D．①③④

E．②③④

某实验小组设计了如图(a)所示的实验装置，通过改变重物的质量，利用计算机可得滑块运动的加速度a和所受拉力F的关系图像。他们在轨道水平和倾斜的两种情况下分别做了实验，得到了两条a-F图线，如图(b)所示。滑块和位移传感器发射部分的总质量m="_____________" kg；滑块和轨道间的动摩擦因数μ=_____________。(重力加速度g取，最大静摩擦力等于滑动摩擦力)

获准占用耕地的单位或者个人应当在（）缴纳耕地占用税。

A.实际占用耕地之日起10日内

B.实际占用耕地之日起30日内

C.获准占用耕地之日起30日内

D.收到土地管理部门的通知之日起30日内

Networks can be interconnected by different devices. In the physical layer, networks can be connected by (11) or hubs, which just move the bits from one network to an identical network. One layer up we find bridges and switches, which operate at data link layer. They can accept (12) ,examine the MAC address, and forward the frames to a different network while doing minor protocol translation in the process. In the network layer, we have routers that can connect two networks. If two networks have (13) network layer, the router may be able to translate between the packer formats. In the transport layer we find transport gateway, which can interface between two transport connections. Finally, in the application layer, application gateways translate message (14) . As an example, gateways between Internet e-mail and X.400 e-mail must (15) the e-mail message and change various header fields.

12（）

A.frames

B.packets

C.packages

D.cells