函数f（x）=log2（x2-x+a）在[2，+∞）上恒为正，则a的取值范围是

阅读理解。

     People know the dangers of fires. It's good for a family to learn how to prepare for a fire. Here are

some suggestions:

    ● put a smoke alarm in the house. Smoke from a fire causes the alarm to go off. The alarm makes

         a loud sound. The sound tells everyone to leave the house at once.

    ● Make escape plans. They should know all the ways out of the house. If there is a fire, everyone

         follows the plan to go out. Part of the plan is to check all the windows to make sure they can be

         opened easily.

    ● Put the extingushers (灭火器) in the house. Practise for a fire. They do fire pratice because they

         teach childen about fire safety. Every-one in the family should know the following fire rules.

    ● Don't open a hot door! The fire can grow more quickly if you open the door.

    ● Stay close to the door! Smoke can be more dangerous than fire. The best air is near the floor because

         smoke rises.

    ● What will you do if your hair or clothes start to burn? First, stop! Don't run! The fire burns faster

         because of more air. Drop! Fall to the floor! Rolling over and over will make the fire go out. Put a

         wet blanket (毯子) around you to keep air away from the fire that may still be on you.

    ● There are many possible causes for fires. A wise family is ready all the time.If there is a fire, don't

         forget to call 119 for help.

1. What does it mean when a smoke alarm rings at home? [ ]

A. You have to get up

B. Water is running to the floor

C. Something is burning

D. Someone breaks your window

2. The writer advises people to do the folowing to prepare for a fire except that ______. [ ]

A. they practise for a fire

B. they make escape plans

C. they buy fire extingguishers

D. they use electrical cookers

3. When a fire happens, ______ if you open the hot door. [ ]

A. the fire will grow more quickly

B. the electricity will be cut off

C. the door will soon be on fire

D. the house will fall down

4. What are the right steps you should take when your hair or clothes catch fire? [ ]

A. Stop, run, roll

B. Stop, drop, roll

C. Run, drop, roll

D. Roll, drop, stop

5. What is the best title for this passage? [ ]

A. The Dangers of Fire

B. The Causes of a Fire

C. Learn to use a Fire Extinguisher

D. Be ready for a fire

报表的输出形式包括（）。

A.屏幕显示

B.打印输出

C.网络传输

D.文件格式转换

军团菌肺炎首先出现在哪个国家（）

A.法国

B.美国

C.英国

D.日本

E.加拿大

关于颅内硬膜下血肿，下列说法错误的是（）

A.源于桥静脉撕裂

B.位于硬脑膜与蛛网膜之间

C.老年人可无明确外伤史

D.常呈新月形

E.CT均表现为高密度

链路预算的目的在于通过（），解出传播路径损耗，从而确定（），计算网络规模。