问题 单项选择题

为降低乘客的眩晕感,“高速列车”的车里安装了减速玻璃。下列关于减速玻璃和普通玻璃的表述正确的是( )。

A.减速玻璃的平面度比普通玻璃更好
B.减速玻璃增强了光的折射作用
C.透过普通玻璃,窗外的物体运动的速度看起来和实际速度一致
D.透过减速玻璃,窗外物体的运动看起来更模糊

答案

参考答案:A

解析: 减速玻璃并不能让外界景物的运动看起来比实际更慢,而是看起来和买际速度一致——和没有玻璃时一模一样,因此所谓减速玻璃准确的名字应该叫“不增速玻璃”。而其他的普通玻璃,相对而言,可以称为“增速玻璃”。减速玻璃准确地矫正了玻璃在厚度、平面度(对于弯曲的玻璃则是曲率)的误差。故选A。

单项选择题

E

Long ago there lived in the mountains a small dragon named Marvin. Like all the other dragons, Marvin had hard skin, a long tail, wings for flying, and a breath of fire. However, Marvin was different from the others. He was friendly like a dog and smart like an elephant.

Three large dragons, Bord ,Brun ,and Barg, delighted in scaring and teasing(戏弄) the other animals on the mountain. One day a goat got lost and came to a place where Bord, Brun, and Barg were sitting. The dragons surrounded the goat and began to tease it. They breathed fire at it and burned its wool. They hit it with their long tails. The scared goat was desperate(拼命) to get away from the three large dragons.

Marvin was flying overhead. He saw what the dragons were doing and landed on a cliff above them. "Excuse me!" Marvin shouted clown to the dragons. "Which of you is the pest dragon"

"The old man with magical powers who lives on the other side of the mountain wants to find the pest dragon, "answered Marvin. "So which of you is the pest"

"I am!" Shouted Bord, and he lifted up a huge rock over his head. He swayed under the weight of the rock but held it p.

"I am!" Shouted Brun, and he grabbed the tops of two trees. He bent them towards each other so the tops touched and held them p.

"I am! "shouted Barg, and he drank all the water out of the mountain lake. His stomach swelled like a balloon, but he held the water p.

As the three dragons showed their strength, Marvin flew down to the goat and gently picked it up. "Come now, small one," Marvin said to the goat. "Let us go quickly to the old man and tell him that we have found the three pest dragons in all the land!\

Marvin was able to help the goat because().

A.he was bigger than the other dragons

B.he was per than the other dragons

C.he was smarter than the other dragons

D.he could fly faster than the other dragons

单项选择题