下列关于加速度的说法中正确的是（） A.加速度表示运动速度的增_爱下问搜题

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问题多项选择题

下列关于加速度的说法中正确的是（）

A.加速度表示运动速度的增加量

B.加速度的方向总是和速度方向相同

C.加速度表示速度变化的快慢

D.加速度在数值上等于单位时间内速度的变化量

答案

参考答案：C, D

解析：

加速度是表示物体速度变化快慢的物理量，A错误C正确，当加速度方向和速度方向相同时，物体做加速运动，相反时，做减速运动，B错误；根据公式可得加速度在数值上等于单位时间内速度的变化量，D正确，故选CD。

完形填空

One sunny afternoon, a seven-year-old girl went for a walk. She crossed a large area of grassland into the woods    21  she realized that she was lost.
Sitting on a rock and   22  what to do, she began crying. After a while. She 23 to walk along a wide path lined with tall trees and thick bushes.   24  it was getting dark, she saw a small, dark wooden house. She opened the door and   25 stepped in. Suddenly, she heard a strange noise, and she ran out the door and back to the   26 . Cold and tired, she fell asleep near a   27 .
The girl’s parents were out and her dog, Laddy, was at home. Laddy   28  that his mistrees（女主人）was in danger. He jumped   29  a window, breaking the glass. He looked in the fields. But he couldn’t find his mistress anywhere. However, from the ground came a   30 scent (气味) as he lowered his head. He 31  the scent and walked across the grassland. Barking   32  into the air, the dog   33  through the woods until he found the 34  . But the girl was not there, so he headed back to the woods. Much to his
35 , he saw his mistress’ blue shirt in the distance. He   36 over some bushes and saw the little stream, where the girl was   37 .
When she opened her eyes and   38  her dog standing beside her, the girl said, “you
39 me, Laddy,” and she kissed him several times. Seeing their daughter and dog coming back, the parents burst into tears of   40 That night Laddy had a heror’s supper: a huge meal of steak

A．remembering

D．unwillingly

B．disappointment

C．embarrassment

D．satisfaction

单项选择题

荀子曰：“天行有常，不为尧存，不为桀亡。”这句话蕴涵的哲理是（）

A.规律具有客观性

B.在规律面前人是无能为力的

C.人可以认识和创造规律

D.一切事物的变化都是发展