The most important reason that life can exist on Earth is its atmosphere--the air around us. __(11)__ it, plant and animal life could not have __(12)__. There would be no clouds, weather, or even sounds, __(13)__ a deathlike stillness and an endlessly black sky. Without the protection of the atmosphere, the sun‘s rays would roast the earth by day. At night, with no blanketing atmosphere, the stored heat would escape into space, __(14)__ the temperature of the planet hundreds of degrees.
Held captive by Earth‘s gravity, the atmosphere surrounds the planet to a depth of hundreds of miles. However, all __(15)__ 1 percent of the atmosphere is in a layer about 20 miles deep just above the surface of the Earth. It is __(16)__ up of a mixture of gases and dusts. About 78 percent of it is a gas __(17)__ nitrogen, which is very important __(18)__ food for plants. Most of the remaining gas, 21 percent, is oxygen, __(19)__ all people and animals depend on for life. The remaining 1 percent is composed of a blend of other gases, __(20)__ carbon dioxide, argon, ozone, and helium--and tiny dust particles. These particles come from ocean salt crystals, bits of rocks and sand, plant pollen, volcanic ash and even meteor dust.
- 9 年前最佳解答
p.s. 我阿只是一名高中生~ 偶爾看到倪的問題上來幫倪解惑~
當然希望沒有答錯xD 因為對英文有興趣 所以看這道題目憑著
填選項也要視文意而定~ 我的答案是這樣辣~ 明天我去問問老師我的解法對不對 再來回覆倪歐~● ˇ ●
2011-03-23 18:02:51 補充：
拍卸~13 15 答案對調~
all but = only參考資料： 我的直覺＝ˇ＝, 一枚高中生的我