我国车辆齿轮油分为（）三类。A、普通车辆齿轮油 B、寒区专用齿轮油 C、中负荷车辆齿

真理是没有阶级性的，在真理面前人人平等。这是因为（）。

A． 真理是绝对性和相对性的统一，真理是不断发展的

B． 真理是具体的，任何真理都有其适用的条件和范围

C．真理就是客观规律，真理与人的阶级地位无关

D．真理具有客观性，真理中包含着不依赖于人类的客观内容

期权交易中的选择权，属于交易中的（）

A.买方

B.卖方

C.双方

D.第三方

能量扩散

被征收房屋价值评估时，应当考虑被征收房屋的( )因素的影响。

A．房屋租赁
B．房屋用途
C．房屋抵押
D．房屋查封

The network layer provides services to the transport layer. It can be based on either___20___. In both cases, its main job is ___21___ packets from the source to the destination.

In network layer, subnets can easily become congested, ncreasing the delay and ___22___ for packets. Network designers attempt to avoid congestion by proper design. Techniques include___23___ policy, caching, flow control, and more.

The next step beyond just dealing with congestion is to actually try to achieve a promised quality of service. The methods that can be used for this include buffering at the client, traffic shaping, resource___24___, and admission control. Approaches that have been designed for good quality of service include integrated services (including RSVP), differentiated services, and MPLS.

20（）

A. virtual circuits or datagrams

B. TCP or UDP

C. TCP or IP

D. IP or ARP