The Lights of Aurora
On the night of 2 September 1859, the dark sky over Europe and North America was suddenly full of light! The light did no come from the sun or the moon and it had a strange colour. The light moved across the sky, (21)______ (come) and going, like clouds in a strong wind In the United States, a man in Boston was using the telegraph to speak to a man in Portland 160km away They both turned off the electricity for the telegraph, but (22)______ could still speak to each other for the next two hours. The electricity was coming from the light in the sky. How was this possible? And what was the light in the sky?
The light is called the aurora. Usually, you can see it only at the very north of the earth, (23)______ it is called aurora borealis or Northem Lights, or at the very south, where it is the aurora australis or Southern Lights. But in 1859, something happened in the sun-a very large storm-and it moved the aurora across the middle of the earth. We do not think that his ever happened before 1859, and we know that it (24)______ (not happen) since then.
Why does the aurora happen? And why can we only see it at the top or bottom of the earth The aurora is made by something (25)______ (call) the 'solar wind' (wind from the sun). We cannot see this wind, or touch it. It is a wind of particles that travel away from the sun at the time at about 400 kilometers a second. Most of the particles never touch the earth The earth has a kind of 'wall' around it that defends it (26)______ these particles. This wall is called the earth's magnetic field, and it pushes the particles away on either side, But the earth's magnetic field has two "windows" in it: the magnetic north, and the magnetic south. At these places, the earth's magnetic field turns down into the earth. And some of the particles from the solar wind come through these magnetic 'windows'. These solar particles crash is to the particles tat are already in our sky. And (27)______ this happens. we see the beautiful lines or clouds of light of the aurora.
Alaska is a good place (28)______ (see) the aurora borealis, and you can also go to places like Iceland, Siberia, the north of Greenland, Norway, Sweden, and Scotland To seethe aurora australis, go to the south of Australia, Tasmania, or New Zealand.
People travel thousands of kilometers to see the aurora, and they can never be sure (29)______ it will happen. But (30)______ do see it say that they will never forget it.
文章解析
这是一篇关于极光（Aurora）的科普短文，包含了英语语法填空练习。
填空答案及解析：
(21) coming：现在分词作伴随状语，表示光在天空中“来来去去”。
(22) they：代词，指代前文提到的“波士顿的男子和波特兰的男子”两人。
(23) where：关系副词引导非限制性定语从句，指代在地球最北端这个地方。
(24) hasn't happened：现在完成时。根据时间状语 "since then"（自那以后），表示动作从过去持续到现在。
(25) called：过去分词作后置定语，表示“被称为……的”。
(26) from：固定搭配 "defend...from..."，意为“保护……免受……”。
(27) when：连词引导时间状语从句，意为“当……的时候”。
(28) to see：动词不定式作后置定语，修饰 "place"（看极光的地方）。
(29) whether / if：引导宾语从句，表示“是否”。
(30) Those / People：代词作主语，指代“那些看到极光的人”。
全文翻译
极光
1859年9月2日夜晚，欧洲和北美的黑暗天空突然充满了光芒！这光并非来自太阳或月亮，而且颜色奇特。这光在天空中移动，（21）来来去去，如同强风中的云彩。在美国，波士顿的一名男子正用电报与160公里外波特兰的一名男子交谈。他们二人都关掉了电报的电源，但（22）他们在接下来的两个小时里仍然能够互相交谈。这电力来自天空中的光。这怎么可能？天空中的光又是什么？
这种光叫做极光。通常，你只能在地球的最北端看到它，（23）在那里它被称为北极光（aurora borealis），或者在最南端，在那里它被称为南极光（aurora australis）。但在1859年，太阳发生了一些事情——一场非常大的风暴——它将极光移动到了地球的中部。我们认为这在1859年之前从未发生过，并且我们知道自那以后它（24）再也没有发生过。
极光为什么会发生？为什么我们只能在地球的两极看到它？极光是由一种叫做（25）“太阳风”的东西产生的。我们看不见也摸不着这种风。它是一股粒子流，以每秒约400公里的速度从太阳向外传播。大部分粒子从未接触地球。地球周围有一种“墙”来保护它（26）免受这些粒子的侵害。这堵墙叫做地球磁场，它将粒子推向两边。但是地球磁场有两个“窗口”：磁北极和磁南极。在这些地方，地球磁场向下转入地球内部。一些来自太阳风的粒子穿过这些磁“窗口”进入。这些太阳粒子与天空中已有的粒子相撞。当（27）这发生时，我们就看到了极光那美丽的线条或光云。
阿拉斯加是（28）观看北极光的好地方，你也可以去冰岛、西伯利亚、格陵兰岛北部、挪威、瑞典和苏格兰等地。要看南极光，就去澳大利亚南部、塔斯马尼亚或新西兰。
人们不远千里去观看极光，但他们永远无法确定（29）是否会看到。但是（30）那些亲眼目睹了极光的人说，他们将永远不会忘记。
一、 重点单词 (Key Vocabulary)
aurora /ɔːˈrɔːrə/ n. 极光（常与 aurora borealis 北极光、aurora australis 南极光搭配）
telegraph /ˈtelɪɡræf/ n. 电报
electricity /ɪˌlekˈtrɪsəti/ n. 电，电力
magnetic field /mæɡˈnetɪk fiːld/ n. 磁场
particle /ˈpɑːtɪkl/ n. 粒子，微粒（指太阳风中的微粒）
defend /dɪˈfend/ v. 防御，保卫
crash /kræʃ/ v. 碰撞，撞击（常搭配
crash into）solar wind /ˈsəʊlə wɪnd/ n. 太阳风
somewhere / somewhere else 某处 / 别处（文中提及的冰岛、西伯利亚等地）
permanent / memorable (扩展) 虽然不是文中原词，但与文章描述“never forget”相关。
二、 重点短语 (Key Phrases)
be full of ... 充满……
例句：The sky was suddenly full of light.
turn off 关闭（电源、电灯等）
例句：They both turned off the electricity.
come and go 来来去去，忽隐忽现
例句：The light moved across the sky, coming and going.
at the very north/south 在最北端/最南端
注：这里
very用作形容词，表示“恰好的，极端的”，起强调作用。at about ... kilometers a second 以大约每秒……公里的速度
注：表示“以……速度”时，介词用 at，例如：at 400 kilometers a second*。
defend ... from ... 保护……免受……
注：文中用到过去分词短语修饰墙（wall that defends it from these particles），即“保护地球免受粒子侵害的墙”。
on either side 在（两边的）每一侧
例句：It pushes the particles away on either side.
turn down into 转向下进入……
例句：The earth's magnetic field turns down into the earth.
come through 穿过
例句：Some of the particles come through these magnetic 'windows'.
crash into 撞击，碰撞（此处指太阳粒子与高空大气粒子碰撞）
thousands of kilometers 数千公里
be sure whether... 确定是否……
例句：They can never be sure whether it will happen.
三、 重点句型 (Key Sentence Structures)
1. 非限制性定语从句（补充说明地点）
原句： You can see it only at the very north of the earth, where it is called aurora borealis.解析：
where引导非限制性定语从句，指代前面的at the very north of the earth，用来补充说明在“那里”它叫什么名字。这是英语中很常见的补充地点的句式。
2. 过去分词作后置定语
原句： The aurora is made by something called the "solar wind".解析：
called是过去分词，放在名词something后面作后置定语，表示“被称为/叫做……的东西”。相当于定语从句something that is called...。
3. 定语从句（修饰物 / 修饰“墙”）
原句： The earth has a kind of 'wall' around it that defends it from these particles.解析：
that引导限制性定语从句，修饰先行词wall（这堵墙保护地球免受粒子侵害）。
4. 时间状语从句（当……的时候）
原句：When this happens, we see the beautiful lines or clouds of light of the aurora.解析：
When引导时间状语从句，表示“当粒子碰撞发生时”，主句描述随之产生的极光现象。
5. whether 引导的宾语从句（表示“是否”）
原句： But they can never be sure whether it will happen.解析：
whether引导宾语从句，作sure的宾语（也可以理解作形容词后的宾语从句），表示“是否能发生”。常见搭配be sure whether / if。
6. 定语从句 + 强调助动词 do
原句： But those who do see it say that they will never forget it.解析：
those who...：是典型的“代词+定语从句”结构，意思是“那些……的人”。
do see it：这里的do是强调助动词，用来强调谓语动词see，意为“确实看到”。整句翻译为：“但是那些确实看到它的人说，他们永远不会忘记。”
