已知函数f(x)=x(x-a)(x-b),点A(s,f(s)),B(t,f(t)

题型:解答题

问题:

已知函数f(x)=x(x-a)(x-b),点A(s,f(s)),B(t,f(t)).
(1)若a=0,b=3,函数f(x)在(t,t+3)上既能取到极大值,又能取到极小值,求t的取值范围;
(2)当a=0时,
f(x)
x
+lnx+1≥0
对任意的x∈[
1
2
,+∞)
恒成立,求b的取值范围;
(3)若0<a<b,函数f(x)在x=s和x=t处取得极值,且a+b<2
3
,O是坐标原点,证明:直线OA与直线OB不可能垂直.
考点:函数的极值与导数的关系函数的最值与导数的关系
题型:解答题

可导致中性粒细胞减少的是()。

A.脾功能亢进

B.金黄色葡萄球菌感染

C.急性心肌梗死

D.大面积烧伤

E.糖尿病酮症酸中毒

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He held the blazing(点燃) matches to a piece of wood. After a while, he became aware that he could smell his hands burning. Then he began to feel the pain. He opened his hands, and the blazing matches fell on to the snow. The flame went out in a puff of gray smoke.

The man looked up. The dog was still watching him. The man got an idea. He would kill the dog and bury his hands inside its warm body. When the feeling came back to his fingers, he could build another fire. He called to the dog. The dog heard danger in the man's voice. It backed away.

The man called again. This time the dog came closer. The man reached for his knife. But he had forgotten that he could not bend his fingers. He could not kill the dog, because he could not hold his knife.

The fear of death came over the man. He jumped up and began to run. The running began to make him feel better. Maybe running would make his feet warm. If he ran far enough, he would reach his friends at Henderson Creek. They would take care of him.

It felt strange to run and not feel his feet when they hit the ground. He fell several times. He decided to rest a while. As he lay in the snow, he noticed that he was not shaking. He could not feel his nose or fingers or feet. Yet, he was feeling quite warm and comfortable. He realized he was going to die. Well, he decided, he might as well take it like a man. There were worse ways to die. The man closed his eyes and floated into the most comfortable sleep he had ever known.

The dog sat facing him, waiting. Finally, the dog moved closer to the man and caught the smell of death. The animal threw back its head. It let out a long, soft cry to the cold stars in the black sky.

And then it tuned and ran toward Henderson Creek... where it knew there was food and a fire.

小题1:Put the following statements in the correct order.

① The thought to kill the dog occurred to the man.

② The man failed to build a fire.

③ The dog headed for Henderson Creek.

④ The man’s life came to an end.

⑤ The man tried to warm by running on his frozen feet.

A.②①⑤④③

B.①②⑤③④

C.①②③④⑤

D.②①⑤③④小题2:Why did the dog back away from the man?

A.It never trusted human.

B.It smelt food somewhere.

C.It sensed murderous atmosphere.

D.It caught sight of the knife..小题3:What does the underlined word “it” mean in the 5th paragraph?

A.The dog.

B.The weather.

C.The death.

D.The cry.小题4:It can be concluded from the passage that________.

A.Man can conquer nature.

B.the man tried hard to survive

C.the dog obeyed human beings .

D.the man met death without dignity.

题型:解答题

治疗超广谱β内酰胺酶(ESBL)阴性杆菌感染最有效的药物是()

A.半合成青霉素

B.第3代头孢菌素

C.碳氢酶烯类抗生素

D.糖肽类抗生素

E.氨基糖苷类抗生素

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知识获得的首要环节是知识直观。( )

题型:解答题

关于下丘脑激素不正确的是

A.是神经细胞分泌的神经激素
B.都是多肽类激素
C.这类激素的作用方式与神经递质完全相同
D.血管升压素是下丘脑合成的激素

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