如图所示是一质点的v-t图象,下列说法错误的是( ) A.前2s物体做匀加速运动

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问题:

如图所示是一质点的v-t图象,下列说法错误的是(  )

A.前2s物体做匀加速运动,后3s物体做匀减速运动

B.2~5s内物体静止

C.前2s内的加速度是3m/s2,后3秒内的加速度为-2m/s2

D.3s末物体速度是6m/s

考点:匀变速直线运动
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目前大多数提供公共资料的FTP服务器都提供______,Internet用户可随时访问这些服务器而不需要预先向服务器申请账号。

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如何在食品生产阶段中控制产品质量?

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A survey has found that in adolescence (青春期) a lack of physical activity is connected with emotional and behavioral problems. More than 7,000 teenagers in Finland took part in the survey that judged their levels of physical activity and mental and emotional health. Boys who reported less than one hour of physical activity a week were more likely to be anxious and sad than boys who were more active. Girls who were not active had similar problems, and were more likely than boys who were not active to have sleep problems and break school rules.

The researchers concluded that both boys and girls who are not active are more likely than active ones to have social and attention problems.

“Adolescence is already a difficult stage of life-emotionally, mentally and physically,” study author Marko T.Kantomaa said in the American College of Sports Medicine.

“Mixing that with negative mental and emotional effects brought on by lack of physical activity does not help young people enter adulthood smoothly. Physical activity could be a highly effective and relatively easy way to help that transition and could lead to healthy habits for one’s whole life,” Kantomaa said.

Researchers said that evidence suggests that an increase in physical activity helps reduce problems of sadness and anxiety in both adolescents and adults. “It seems that there is a psychological(心理的)and physiological(生理的)connection that helps explain the beneficial effects of exercise on mental health,”Kantomaa said.

1. The first paragraph leads us to believe that________.

A. a lack of physical activity may cause many mental problems

B. a lack of physical exercise is common among teenagers

C. girls have more physical and mental problems than boys

D. inactive boys are more likely to break rules than inactive girls

2. Which of the following problems may NOT be caused by a lack of activity according to the passage?

A. Anxiety.     B. sleeplessness.    C. Inattention.   D. unkindness.

3. From the passage we can conclude that___________.

A. boys take more physical exercise than girls

B. teenagers who aren’t active spend a lot of time studying

C. plenty of physical activity is effective in developing healthy habits

D. physical exercise is the only way to cure mental problems

4. The underlined word “transition” in the fourth paragraph is closest in meaning to“_______”.

A. change      B. condition       C. balance       D. activity

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女患者,子宫下脱,腰酸腿软,小腹下坠,小便频数,夜间尤甚。舌淡红,脉沉弱。治宜:()

A.滋阴养血固摄

B.补肾固脱

C.补气升提

D.清热利湿固脬

E.以上均不是

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弥散性血管内凝血的病因,下列哪一项是最多见的()

A.白血病

B.感染性疾病

C.病理产科

D.免疫性疾病

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