某火车站向贫困失学儿童赞助大批文具是属于促销中的（）策略。

等腰三角形的顶角为40°，则其底角为（    ）度。

如果两个五边形是位似图形，且位似比为5：3，且它们的周长和为240cm，则它们的周长差为______．

(51) is a six bytes OSI layer 2 address which is burned into every networking device that provides its unique identity for point to point communication.

(52) is a professional organization of individuals in multiple professions which focuses on effort on lower-layer protocols.

(53) functions with two layers of protocols. It can connect networks of different speeds and can be adapted to an environment as it expands.

(54) is the popular LAN developed under the direction of the IEEE802.5.

(55) is the popular backbone technology for transmitting information at high speed with a high level of fault tolerance which is developed under the direction of ANSI.

（54）是（）

A.Ethernet

B.TokenBus

C.TokenRing

D.DQDB

五星连珠，也叫“五星聚”。我国古代用以表示水、金、火、木、土五行星同时出现在天空同一方的现象。这种现象不常发生，所以古人曾唯心的认为它是祥瑞。后人推广到只要五行星各居一宫相连不断时就叫做“连珠”。据此回答下列问题：

“五星连珠”中的五颗行星体积和质量最大的是哪一颗（）

A.水星

B.木星

C.金星

D.火星

与同等排量的汽油车相比，柴油轿车能够节油60%以上。