人類與地球的存在發展需要獲得能量，但是大家知道這些能量來自哪裡嗎?下面，我們不妨一起去看看這篇公共英語五級閱讀文章吧。
The Source of Energy
A summary of the physical and chemical nature of life must begin, not on the Earth, but in the Sun; in fact, at the Sun's very center. It is here that is to be found the source of the energy that the Sun constantly pours out into space as light and heat. This energy is liberated at the center of the Sun as billions upon billions of nuclei of hydrogen atoms collide with each other and fuse together to form nuclei of helium, and in doing so, release some of the energy that is stored in the nuclei of atoms. The output of light and heat of the Sun requires that some 600 million tons of hydrogen be converted into helium in the Sun every second. This the Sun has been doing for several thousands of millions of years. The nuclear energy is released at the Sun's center as high-energy gamma radiation, a form of electromagnetic radiation like light and radio waves, only of very much shorter wavelength. This gamma radiation is absorbed by atoms inside the Sun to be reemitted at slightly longer wavelengths. This radiation, in its turn is absorbed and reemitted. As the energy filters through the layers of the solar interior, it passes through the X-ray part of the spectrum eventually becoming light. At this stage, it has reached what we call the solar surface, and can escape into space without being absorbed further by solar atoms. A very small fraction of the Sun's light and heat is emitted in such directions that after passing unhindered through interplanetary space, it hits the Earth.
能量的來源
概說生命的物理和化學特性必須始於太陽——確切地說，是太陽的核心，而非地球。能量來自太陽的核心。 在這裡，太陽不停地以光和熱的形式向空間傾瀉出能量。數十億計的氫原子核在太陽的核心碰撞並且聚變生成氦。在此過程中一部分原本儲存於原子核中的能量被釋放出來。太陽所產生的光和熱需要每秒將六億噸氫轉化為氦。這樣的轉化在太陽中已經持續幾十億年了。核能在太陽的核心被釋放為高能的伽馬射線。這是一種電磁射線，就象光波和無線電波一樣，只是波長要短得多。這種伽瑪射線被太陽內的原子所吸收，然後重新釋放為波長稍長一些的光波。這新的.射線再次被吸收，而後釋放。在能量由太陽內 部一層層滲透出來的過程中，它經過了光譜中X 射線部分，最後變成了光。在此階段，能量到達我們所稱的太陽表層，並且離散到空間而不再被太陽原子所吸收。只有很小一部分太陽的光和熱由此方向釋放出來，並且未被阻擋，穿越星空，來到地球。
附：公共英語五級閱讀技巧之養成二次閱讀習慣，培養邏輯推理能力
很多書上要求學生學會分析文章的結構，其實就是要求學生提高邏輯推理能力。在平時練習中，學生做完閱讀，惟一可做的就是對答案，事實上，糾正答案後對文章的再次閱讀往往至關重要。第一遍讀文章時，我們應當模擬考試的緊張氣氛，儘量高質快速。但，對完答案後，我們有充足的時間再次閱讀文章。第二次閱讀文章我們的目的不在是獲取資訊，而是把握文章的佈局安排，分析作者的意圖。我們必須帶著思考再次閱讀文章，問問自己以下問題：
如果自己寫同樣題目或題材的文章，會採取何種文章佈局?如我們自己設想的佈局與作者不同，那麼具體不同之處在何處?這篇文章與以前讀過的同體裁文章相比，有何特點?
也許有人會說，這樣的訓練不就成了精讀課了嗎?如果時間允許，二次閱讀成了精讀，又有何不可?講求速度的範讀是應試而用，要想真正培養邏輯推理能力，提高閱讀水平，還非精讀不可。文章的是永遠讀不完的，如果想著去讀200篇各種模擬閱讀題，倒不如踏踏實實讀50篇歷年真題。另外，地道的文章分析多了，對自己寫文章佈局謀篇也不無好處。
