For each blank, choose the best answer from the four choices and write down on the answer sheet.

(71) 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.

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

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

(74) is the popular LAN developed under the direction of the IEEE 802.5.

(75) 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.

74（）

A．Ethernet

B．Token Bus

C．Token Ring

D．DQDB

一群风华少女2005年春节晚会上，用精美绝伦的舞蹈把我国佛文化中的"千手观音"演绎得淋漓尽致，给人以美的熏陶，善的启迪。

(1)如图所示，观众看不见邰丽华（领舞者）身后站着的其她舞蹈者，这是因为光的____________的缘故。

(2) 佛光普照，梵音如丝，聆听脱俗乐音，我们能分辨出究竟是何种乐器在发声，因为不同的乐器发声，其_____是不同的。（填“音调”、“音色”或“响度”）

(3)舞台上云雾缭绕，宛如天庭，它们是固态二氧化碳 _______时吸热导致空气中的水蒸气遇冷_________而产生的效果。（填物态变化）

（4)聋哑少女听不清声音，她们是如何感知音乐节奏的？训练中，技术人员通过加大音量，使音箱、舞台产生___________，从而使靠在音箱上或站在舞台上的聋哑少女感觉到音乐节奏的变化。