题目内容

活塞环的密封原理是（）。

A. 阻塞为主，兼有节流
B. 节流为主，兼有阻塞
C. 只有阻塞
D. 只有节流

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活塞式压缩机气阀常用结构形式是（）。

A. 环状阀
B. 网状阀
C. 直流阀
D. 组合阀

Write the correct paragraph number from the reading next to its main idea.①Silk was highly valued by rich Europeans.②Deadly illnesses were carried by travelers on the Silk Road.③Although the Silk Road brought many good changes to the world, it also brought bad changes.④The Silk Road is a collection of roads that joined the East and West.⑤As people from different countries met, cultures began changing.

A. 25641
B. 25614
C. 26514
D. 24615

橱窗设计,它不仅仅是审美功能的展示，而是实用功能的强化。橱窗的直接作用在于消费者看到橱窗后能立见功效，而不是无动于衷。

A. 对
B. 错

消费者在感知认识橱窗的这一过程，实际上就是视觉流程。

A. 对
B. 错