新东方名师推荐:四六级优秀范文背诵(45)

最后冲刺

★ 2010年四六级备考手册：听力篇（更新中…）

★ 2010年四六级备考手册:阅读篇(更新中…)

★ 2010年四六级备考手册：写作篇（更新中…）

考前必备

★ 四级写作高分工具：新概念3常见词汇句法

★ 名师指导6月六级最后冲刺备考方法

★ 四六级名师传授绝技：5个词拿下快速阅读

★ 2010年6月六级听力考试场景词汇精要

★ 六级听力长对话短期突破：从真题入手

2010年6月四六级考试真题答案点评汇总

45.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 librated 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 year.

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.

四级历年真题（2001-2009）

2001年1月	2001年6月	2002年1月	2002年6月	2003年1月
2003年6月	2003年9月	2004年1月	2004年6月	2005年1月
2005年6月	2005年12月	2006年6月	2006年12月	2007年6月
2007年12月	2008年6月	2008年12月	2009年6月	2009年12月

六级历年真题（2001-2009）