一物体做加速直线运动，依次通过A、B、C三点，AB=BC，物体在AB段_爱下问搜题

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问题选择题

一物体做加速直线运动，依次通过A、B、C三点，AB=BC，物体在AB段的加速度为a₁，所用时间为t₁，在BC段的加速度为a₂，所用时间为t₂，且物体在B点的速度为V_B=

VA+VC

2

，则（　　）

A．a₁=a₂

B．a₁＞a₂

C．t₁=t₂

D．t₁＞t₂

答案

通过图线可以看出，两端位移相等，即图线与时间轴所围成的面积相等，可以得出BC段图线的斜率大于AB段图线的斜率，所以a₁＜a₂．

由图线可知，t₁＞t₂．故D正确，A、B、C错误．

完形填空

完形填空。

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bedroom, and began to 2 a letter to her mother. 3 the letter, she said she would like to go on a picnic and open her
presents during the picnic. Clara gave her mom the letter and her mom said, "Thanks, dear. Go to bed 4 I'll read it."
Clara went to bed with her favorite teddy bear. Her mom 5 her face and said, "Good night."
     Early next morning, Clara put on her 6 and went to the living room. Her mom was 7 things for the picnic. After
breakfast, the family 8 their car to the park. They found a good place.   Clara unwrapped her presents. There were
beautiful skirts, dolls and books. Finally, Mom took out the last present. It was a 9 box. Clara opened the box and
found a pot. A lovely fish was swimming in it. Clara was so happy. Now, she still remembers that birthday 10 .

( )1. A. surprised
( )2. A. send
( )3. A. On
( )4. A. but
( )5. A. saw
( )6. A. bags
( )7. A. making
( )8. A. drove
( )9. A. broken
( )10.A. right now

B. pleased
B. draw
B. In
B. so
B. washed
B. clothes
B. planting
B. mended
B. ugly
B. at first

C. relaxed
C. write
C. From
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C. all the time

D. worried
D. find
D. Before
D. or
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D. gloves
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D. just now

单项选择题

对决定扣押的物证、书证，要查点清楚，当场开列清单( )。

A．一式一份
B．一式二份
C．一式三份
D．一式四份