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问题 选择题

已知函数f（x）=lg（ax2+2x+1），命题p：若f（x）的定义域为R，则0≤a≤1；命题q：若f（x）的值域为R，则0≤a≤1．那么（　　）

A．p真q假

B．p假q真

C．“p或q”为假

D．“p且q”为真

答案

因为f（x）的定义域为R，所以ax2+2x+1＞0对一切x∈R成立．

由此得

a＞0
△=4-4a＜0

解得a＞1．

又因为ax2+2x+1=a（x+

1
a
）2+1-
1
a
＞0，

所以f（x）=lg（ax2+2x+1）≥lg（1-

1
a
），

所以实数a的取值范围是（1，+∞），

故命题p是假命题．

（2）因为f（x）的值域是R，所以u=ax2+2x+1的值域⊇（0，+∞）．

当a=0时，u=2x+1的值域为R⊇（0，+∞）；

当a≠0时，u=ax2+2x+1的值域⊇（0，+∞）等价于

a＞0
4a-4
4a
≤0.

解之得0＜a≤1

所以实数a的取值范围是[0.1]．

故命题q是真命题．

故选B．

阅读理解

阅读理解

        A woman finds a purse on the road outside the school gate.She picks it up and opens it. There's

some money in it."Shall I keep the money for myself?" She thinks,"Oh, no.The owner (物主) must be

very worried.I must give it back to the owner."She waits and waits, but no one comes to take the purse

back."I'm very hungry now," the woman says to herself. "Shall I buy something to eat with the money?"

So she goes to a shop. She buys many pens and books. She gives them to some poor buys and girls.

What do you think of the woman?

1.When the woman finds the purse, she first wants to         .

A.keep it for herself

B.give it back to the owner

C.buy some food for herself

2.The women buys          with the money at last.

A.some food

B.some clothes

C.some things

3.The word "poor" is ___ in Chinese.

A. 富有的

B. 穷苦的

C. 快乐的

4. The woman         .

A. must be very happy

B. can't be happy

C. has a lot of money

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单项选择题

生产经营单位进行爆破、吊装等危险作业应当安排( )进行现场安排管理，确保操作规程的遵守和安全措施的落实。

A．工程师

B．负责人

C．专门人员

D．安全员
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