小明的书桌上铺有一块玻璃板,晚上小明在台灯下学习的时候,桌面上的玻璃会“发出”刺

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问题:

小明的书桌上铺有一块玻璃板,晚上小明在台灯下学习的时候,桌面上的玻璃会“发出”刺眼的亮光,为了保护眼睛,采用最简单、效果最好的方法是  [ ]

A.把台灯换为吊灯            

B.把台灯放在正前面    

C.换一个功率小一点的灯泡    

D.把台灯移到左臂外侧

考点:漫反射,镜面反射
题型:选择题

English is the native or official language of one-fifth of the land area of the world. It is spoken in North America, Great Britain, Australia, and New Zealand. In South Africa and India it is one of the official languages.

More people study English than any other language. In many countries, the textbooks in universities are in English. Many university classes are taught in English even though the native language is not English.

English is the language of international communication. It is the language of international business, research, and science. More than three-fourths of the world’s mail is written in English. More than half of the scientific research journals are in English. Most other languages have borrowed many English words.

Why did English become the international language? In the middle of the nineteenth century, French was the international language. The Britain became very powerful in the world. England started colonies in North America and India in the seventeenth century. By 1900 England also had colonies in other parts of Asia, Africa and the South Pacific. The people in the colonies had to use English. Slowly it became more important than French internationally. After the Second World War, the United States became very powerful, and even more people began to learn English.

Is English a good international language? It has more words than any other language. The grammar is simpler than in other major languages. However, English spelling is difficult. Foreigners all have trouble spelling English. So do native speakers!

Since 1880, people have invented over fifty artificial (not natural) languages. No one speaks them as a native language. However, none of them has ever become popular. Some people don’t want to study English, but it is the international language. There is no way to change that now.

小题1:English is the native language of ______.

A.South Africa

B.Australia

C.All of Canada

D.Malaysia小题2:England started a colony in India in the ______.

A.1600s

B.1800s

C.1700s

D.1900s小题3:Which of the following is NOT TRUE according to the text?

A.The English grammar is simple in general.

B.It has a good vocabulary.

C.Its pronunciation sounds pleasant.

D.It is difficult to spell correctly.小题4:The author concludes that____.

A.it is necessary to invent a new language.

B.English is the international language whether you like it or not

C.English is much better than other languages

D.English should be spoken all over the world

题型:选择题

电场中任意两点间的电压,等于这两点电位之()。

A.和

B.差

C.积

D.商

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(12分)如图所示,粗糙水平轨道AB与竖直平面内的光滑半圆轨道BDC在B处平滑连接,B、C分别为半圆轨道的最低点和最高点,D为半圆轨道的最右端。一个质量m的小物体P被一根细线拴住放在水平轨道上,细线的左端固定在竖直墙壁上。在墙壁和P之间夹一根被压缩的轻弹簧,此时P到B点的距离为x0。物体P与水平轨道间的动摩擦因数为μ,半圆轨道半径为R。现将细线剪断,P被弹簧向右弹出后滑上半圆轨道,恰好能通过C点。试求:

(1)物体经过B点时的速度的大小?

(2)细线未剪断时弹簧的弹性势能的大小?

(3)物体经过D点时合力的大小?

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在已拉下的总开关上应挂上“()”的警告牌。

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在建筑安装企业的生产活动中,应力求用最少的人力、物力,生产出质量合格的建筑产品,获得最好的经济效益。( )

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