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4. What did the explorers find?

A. The coastlines of South America and Africa could fit together.

B. The coastlines of North America and Africa could fit together.

C. The east coastlines of North America and the west coast of Europe could fit together.

D.The coastlines of North America and India could fit together.

(二)

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Now this is the way to add new words to your vocabulary! Word Smart Junior will make you laugh so much. You’ll be amazed that you’ve just learned more than 120 fascinating and very useful words! Parents, teachers, and friends will marvel at your eloquence (口才)!

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試題詳情

3. The last word of the third paragraph “tectonics” mean “________”.

A. study of construction

B. study of architecture

C. earth surface

D. structural geology

試題詳情

2. Which of the following is true according to the passage?

A. We didn’t see the Earth from far away until we saw the picture taken in the space.

B. Our ancient thought that the surface of the earth is still.

C. Alfred Wegener was not the first person to investigate the idea that the continents move.

D. The coastline of India and Africa fit together.

試題詳情

1. What does the writer mainly tell us in the passage?

A. The first breath-taking pictures of the Earth taken from space.

B. Human’s recognition of the earth’s surface.

C. The German scientist Alfred Wegener.

D. The early explorers’ discovery.

試題詳情

　　如圖是一種建立在空間的太陽能電站向地球上固定區(qū)域供電的示意圖。在太陽能收集板上鋪設(shè)太陽能電池，通過光電轉(zhuǎn)換把太陽能轉(zhuǎn)換成電能，再經(jīng)微波轉(zhuǎn)換器將電流轉(zhuǎn)換成微波，并通過天線將電能以微波的形式向地面發(fā)送。地面接收站通過天線把微波能還原成電能。

　　(1)如果太陽能電池的硅片能提供的電能為12kW/m²，巨大的太陽能收集板的總面積為5×10⁶m²，則太陽能電站的發(fā)電能力是多少kW？

　　(2)利用微波傳輸電能，實現(xiàn)了“無纜輸電”。輸電效率可達80%，若微波輸電采用的頻率是2450MHz。求微波的波長及地面接收站接收到的電能是多少kW？

　　解析：從題目和問題中可提取有用的信息并推導出公式，然后利用公式進行計算。

試題詳情

　　如圖(甲)所示，光I從空氣斜射如玻璃中，發(fā)生了折射現(xiàn)象，從圖中可以看出折射角r小于入射角i。那么，一般情況下，i與r有什么定量關(guān)系呢？1621年，荷蘭學者斯涅爾通過實驗終于找到了i與r之間的規(guī)律，如圖是光從空氣進入玻璃中時，利用實驗數(shù)據(jù)得到的sinr與sini的關(guān)系圖象。