若f′(x0)=2,则limk→0f(x0-k)-f(x0)2k等于( ) A.-

题型:选择题

问题:

若f′(x0)=2,则
lim
k→0
f(x0-k)-f(x0)
2k
等于(  )
A.-1B.-2C.1D.
1
2
考点:函数的极值与导数的关系
题型:选择题

Do you like to sit in front of the computer and play computer games hour after hour? Have you ever thought of what that may be doing to your health? More and more children are becoming overweight(肥胖的) and growing less creative because they spend too much time in front of the computer according to a survey.

Last week Child Protective Services(儿童保护组织)in America organized an activity. The aim of the activity was to encourage children to do some outdoor activities instead of playing computer games at home. Many American children spend about 1,000 hours a year playing computer games — more time than they spend in school. As a result, they are overweight. Some of them have very poor eyesight, and they can’t see clearly.

Everyone should pay attention to his health and try to keep healthy. The doctor says that the longer children play computer games, the more overweight they may become. And the junk food children eat while they’re playing computer games makes the weight problem more serious.

To keep fit, children need to take exercise regularly, play outside with friends, and explore the world around them. Can you spend two weeks without playing computer games? It might be difficult for computer lovers, but why not have a try?

小题1:Children may become______ if they play computer games all day.

A.much younger

B.much lighter

C.less creative

D.less careful小题2:American children may spend______ hours in school a year according to the passage.

A.less than 1,000

B.more than 1,200

C.about 1,500

D.about 2,000小题3:The underlined word “eyesight” means “______” in Chinese.

A.凝聚力

B.想象力

C.记忆力

D.视力小题4:What can we learn from the passage?

A.Playing computer games has caused some health problems.

B.Playing computer games can make children cleverer and more creative.

C.Child Protective Services in America organized an activity for parents.

D.Child Protective Services asked children to study at home and not to play outdoors.

题型:选择题

关于图的叙述,正确的是(  )

A.读该图时,应采用“上北下南,左西右东”的规定确定方向

B.河流大致由北向南流

C.公路AB段大致为东西走向

D.公路BC段大致为东西走向

题型:选择题

胸腔闭式引流护理措施不正确的是()。

A.病人宜采取半卧位

B.引流管双固定

C.定时挤压引流管

D.水封瓶液面低于引流管胸腔出口平面60cm

E.观察术后引流量,不超过150ml/h

题型:选择题

既能凉血止血,又能清热利尿,清肺胃热的药物是()

A.大蓟

B.小蓟

C.白茅根

D.地榆

E.槐花

题型:选择题

1900年,命令清军斩杀义和团,并无耻地请求八国联军“助剿”的卖国贼是()

A、袁世凯

B、慈禧太后

C、李鸿章

D、荣禄

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