已知a+b=2,ab=-2,则(a-b)2=______.

题型:填空题

问题:

已知a+b=2,ab=-2,则(a-b)2=______.

考点:完全平方公式
题型:填空题

将下列液体分别与溴水混合并振荡,静置后分为两层,两层几乎均呈无色的是[ ]

A.氯水

B.己烯

C.苯

D.碘化钾溶液

题型:填空题

如图所示,一劲度系数为k = 800N/m的轻弹簧两端各焊接着两个质量均为m = 12kg的物体A、B。物体A、B和轻弹簧竖立静止在水平地面上,现要加一竖直向上的力F在上面物体A上,使物体A开始向上做匀加速运动,经0.4s物体B刚要离开地面,设整个过程中弹簧都处于弹性限度内,取g = 10m/s2,求:

(1)此过程中所加外力F的最大值和最小值。

(2)此过程中外力F所做的功。

题型:填空题

突发公共卫生事件包括()

A、重大传染病疫情

B、群体性不明原因疾病

C、重大食物和职业中毒

D、其他严重影响公众健康的事件

题型:填空题

阅读理解。

     The past ages of man have all been carefully labeled by anthropologists (人类学家). Descriptions like

"Palaeolithic (旧石器时代的) Man". "Neolithic (新石器时代的) Man",etc..neatly sum up whole periods.

When the time comes for anthropologists to turn their attention to the twentieth century, they will surely

choose the label "Legless Man". Histories of the time will go something like this:"in the twentieth century,

people forgot how to use their legs. Men and women moved about in cars, buses and trains from a very

early age. There were lifts in all large buildings to prevent people from walking. And the surprising thing

is that they didn't use their legs even when they went on holiday."

     The future history books might also record that we were deprived (剥夺) of the use of our eyes. In

our hurry to get from one place to another, we failed to see anything on the way. Air travel gives you a

bird's-eye view of the world. When you travel by car or train, an unclear picture of the countryside

constantly smears the windows. Car drivers, especially, are mixed with the urge to go on and on: they

never want to stop. The typical twentieth-century traveler is the man who always says "I've been there."

You mention the remotest, and someone is bound to say "I've been there"-meaning, "I drove through it at

100 miles an hour on the way to somewhere else."

     When you travel at high speeds, the present means nothing: you live mainly in the future because you

spend most of your time looking forward to arriving at some other place. But actual arrival, when it is

achieved, is meaningless. You want to move on again. By traveling like this, you suspend all experience.

The traveler on foot, on the other hand, lives constantly in the present.

     For him traveling and arriving are one and the same thing: he arrives somewhere with every step he

makes. He experiences the present moment with his eyes, his ears and the whole of his body. At the end

of his journey he feels a delicious physical tiredness. He knows that sound, satisfying sleep will be his: the

just reward of all true travelers.

1. What's the best title of the passage? [ ]

A. The advantages of travel

B. The best way to travel

C. The reward of true travel

D. Possible ways to travel

2. Anthropologists label man nowadays "Legless" because _____. [ ]

A. people forget how to use their legs

B. lifts prevent people from walking

C. modern vehicles have replaced walking

D. people prefer cars, buses and trains

3. While traveling at high speed, _____. [ ]

A. people can get more pleasure from it

B. people always focus on next destination

C. people can enjoy the view of the destination

D. people care much about the arrangement of the journey

4. The author says "we are deprived of the use of our eyes" because _____. [ ]

A. people can't get a clear picture of the view along

B. eyes become useless in traveling at high speed

C. people want to sleep during traveling

D. people won't use their eyes

5. What does the author intend to tell us? [ ]

A. Legs become weaker.

B. There is no need to use legs or eyes.

C. Modern means of transportation make the world a small place.

D. We should experience the present heart and soul while traveling.

题型:填空题

“英国的社会结构不像欧洲大陆那样僵硬死板。没有因袭社会风尚去阻挠拥有土地的士绅经营工商业;没有法律会妨碍一个工匠的社会地位上升。”此段材料主要表明工业革命最早从英国开始是因为()

A.英国经过启蒙运动的充分洗礼

B.英国的殖民扩张使其拥有广阔的海外市场,综合国力强于欧洲大陆

C.资产阶级革命推动了价值观念与法律关系的变革

D.英国与欧洲大陆的历史发展有本质不同

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