No one knows exactly how the earth began, as it happened so long ago. However, according to a widely accepted theory, the univer began with a “Big Bang” that threw matter in all directions. After that, atoms began to form and combine to create stars and other bodies.
For veral billion years after the “Big Bang”, the earth was still just a cloud of dust. What it was to become was uncertain until between 4.5 and 3.8 billion years ago when the dust ttled into a solid globe. The earth became so violent that it was not clear whether the shape would last or not. It exploded loudly with fire and rock. They were in time to produce carbon, nitrogen, water vapor and other gas, which were to make the earth’s atmosphere. What is even more important is that as the earth cooled down, water began to appear on its surface.
Water had also appeared on other planets like Mars but unlike the earth, it had disappeared later. It was not immediately obvious that water was to be fundamental棕色脂肪组织 to the development of life. What many scientists believe is that the continued prence of water allowed the earth to dissolve harmful gas and acids into the oceans and as. This produced a chain reaction, which made it possible for life to develop.
一、词汇
1. matter n. 事件; （讨论、考虑等的）问题; 重要性; 物质;
vi.要紧，重要; 化脓; 有重大影响; 有重要性;
2. combine v. 使结合; 使化合; 兼有;
例：If you combine two or more things or if they combine, they exist together.
3. solid adj. 固体的
4. globe n. 球体
5. violent adj. 暴力引起的;剧烈的，（风，爆炸等）猛烈的，狂暴的;感情强烈的
6. explode vi. 爆[突]发，发怒;激增，迅速扩大
vt. （使）爆炸;突然（发出巨响，活跃起来，迸发感情）
例：And one day the powder 冬季健身keg绑鱼线 may 动漫公主图片explode.
7. nitrogen n. 氮，氮气
8. fundamental adj. 基础的，基本的，根本的，重要的，原始的，主要的，
二、词组和短语
1. throw matter in all directions 把所有的物质丢向四面八方
2. veral billion years 几十亿年 扩展：five billion years 五十亿年 billions of years 几十亿年
类似用法还有：hundred, thousand, million
3. the dust ttled into a solid globe （稳定）形成一个固体的球体
4. in time瞩望 及时 扩展：on time 准时 at time 偶尔 at times 有时，间或
暮春时节5. allow the earth to dissolve 允许地球溶解
扩展：allow sb to do sth 允许某人做某事
allow doing sth允许做某事
6. make it possible for life to develop 使生命发展成为可能
三、句型
1. What is even more important is that as the earth cooled down, water began to ap
pear on its surface. 更重要的是随着地球的冷却下来，水也开始出现在地球的表面上了。
这是一个主语从句，What is even more important是主语，是由what引导的一句话，以下是主语从句的具体考点和用法。
1． 定义：用作主语的从句叫做主语从句。
2． 构成：关联词+简单句
3． 引导主语从句的关联词有三类：
. 从属连词that
例：That they were in truth sisters was clear from the facial remblance between them.
很明显，她们确是亲姐妹，她们的脸型很相似。
. 从属连词whether
例：Whether he’ll come here isn’t clear.
. 连接代词who, whom, who, what, which, whoever, whatever, whichever
连接副词 where, when, how, why
例：What she did is not yet known. 她所做的事情还是未知。
How this happened is not clear to anyone. 任何人都不清楚这件事是如何发生的。
Whoever comes is welcome. 谁来都欢迎。
Wherever you are is my home ---- my only home. 你在哪我的家就在哪----我唯一的家。
其他用法：从句能用it作形式上的主语。常以it作形式主语的句型有：
. It+be+形容词(obvious, true, natural, surprising, good, wonderful, funny, possible, likely, certain, probable, etc.)+that从句
游字开头的成语例：It is certain that she will do well in her exam. 很确定的是她会在考试中取得好成绩。
It is probable that he told her everything. 可能他已经告诉了她一切。
. It+be+名词词组(no wonder, an honor, a good thing, a pity, no surpri, etc.)+that从句。
例：It's a pity that we can’t go. 真遗憾我们不能去。
It's no surpri that our team should have won the game. 我们队赢得了比赛一点也不意外，
. It+be+过去分词(said, reported, thought, expected, decided, announced, arranged, etc.)+that从句
例：It is said that Mr. Green has arrived in Beijing. 据说格林先生已经到了北京。
It is reported that China has nt another man-made earth satellite into orbit.据报道中国发射了另一个人造卫星进入轨道。
. It+em, happen等不及物动词及短语+that从句
例：It ems that Alice is not coming to the party at all. 似乎Alice压根儿就不会来这个派对。
It happened that I was out that day. 它是在我不在家那天发生的。
It+doesn’t matter (makes no difference, etc.)+连接代词或连接副词引起的主语从句
例：It doesn’t matter whether she will come or not. 她来不来无所谓。
It makes no difference where we shall have the meeting.我们在哪儿举行会议都一样。
. 当that引导的主语从句出现在疑问句中时，要以it作形式主语，而把主语从句后置
例：Is it true that the scientist will give us a lecture next week? 下周那位科学家会给我们做演讲是真的吗？
Does it matter much that they will not come tomorrow? 他们明天来不来真的有那么重要吗？
. 当主语从句出现在感叹句中时，要以it作形式主语，而把主语从句后置。
例：How strange it is that the children are so quiet! 孩子们这么安静可真奇怪啊！
注意：连接代词whoever, whatever, whichever等引导主语从句的含义
例：Whoever comes will be welcome. (whoever=the person who) 来的人将受到欢迎。
Whatever he did was right. (whatever=the thing that) 他所做的事情是正确的。
