语法

能力表达 can / could / be able to / manage to (Ability)

语法点：能力表达 can / could / be able to / manage to (Ability)

表示“能、会、有能力做某事”，最常用 can（现在）和 could（过去）。但 can 没有将来时和完成时，这时要用 be able to：will be able to（将来能）、have been able to（一直能）。谈过去时，could 表示过去“一般性的能力”（会游泳、能看见），而“在某个具体场合经过努力成功做到”要用 was / were able to 或 managed to，不用 could。否定句 couldn't 则两种情况都可以用。本课讲飞机成功飞越山脉，所以反复出现 was able to。

结构

时间	一般能力	具体场合做到了
现在	can / am, is, are able to	can
过去	could	was / were able to；managed to
将来	will be able to	will be able to
否定	can't / couldn't / be not able to	couldn't / wasn't able to / didn't manage to

can / could + 动词原形：He can fly a plane.
be able to + 动词原形：The plane was able to rise.
manage to + 动词原形：They managed to clear the mountains.

课文中的例句

[句 2] Though, at first, Byrd and his men were able to take a great many photographs of the mountains that lay below, they soon ran into serious trouble. — were able to 表示在那个具体场合成功拍到了照片。
[句 4] It could only get over the mountains if it rose to 10, 000 feet. — could 用在条件句中，表示当时具备的可能性/能力。
[句 6] The plane was then able to rise and it cleared the mountains by 400 feet. — was able to 强调经过努力（扔掉粮食袋）后成功升高。
[句 7] Byrd now knew that he would be able to reach the South Pole which was 300 miles away. — would be able to 是 will be able to 的过去形式，表示“将能够”，can 没有这种形式。
[句 8] The aircraft was able to fly over the endless white plains without difficulty. — was able to 表示顺利完成了飞行。

补充例句

Byrd could fly a plane when he was a young man. 伯德年轻时就会开飞机。
After they threw out the heavy sacks, the men managed to save the plane. 扔掉沉重的袋子后，他们设法保住了飞机。
If the weather is good, we will be able to see the mountains from the aircraft. 如果天气好，我们将能从飞机上看到群山。

易错点

❌ The plane could rise and cleared the mountains at last. → ✅ The plane was able to rise and cleared the mountains at last. 具体场合“成功做到了”用 was able to / managed to，不用 could。
❌ He knew that he will can reach the South Pole. → ✅ He knew that he would be able to reach the South Pole. can 没有将来形式，两个情态动词不能连用，要用 be able to。
❌ They were able to taking photographs of the mountains. → ✅ They were able to take photographs of the mountains. be able to 后接动词原形。
❌ They managed taking a great many photographs. → ✅ They managed to take a great many photographs. manage 后接 to do，不接 doing。

逐句语法分析 · 8 句

1In 1929, three years after his flight over the North Pole, the American explorer, R.E. Byrd, successfully flew over the South Pole for the first time.
1929年，在飞越北极三年之后，美国探险家R.E.伯德成功地首次飞越了南极。
一般过去时 (Simple Past) · 时间状语 + 同位语 + 主语 + 副词 + 动词过去式 + 地点 + for the first time
- flew 是 fly 的过去式
- the American explorer, R.E. Byrd 是同位语结构
- three years after his flight 说明时间关系
一般过去时叙述历史事件，句首用时间状语交代背景。
2Though, at first, Byrd and his men were able to take a great many photographs of the mountains that lay below, they soon ran into serious trouble.
虽然一开始伯德和他的助手们能够拍下大量下方群山的照片，但他们很快就遇到了严重的麻烦。
一般过去时 (Simple Past) · Though + 主语 + were able to + 动词原形 …, 主语 + 动词过去式 + 宾语
- were able to take 表示具体场合成功做到
- that lay below 是定语从句，lay 是 lie 的过去式
- run into trouble 遇到麻烦
were able to 说明当时成功拍到了照片；though 引导让步从句，与后面的麻烦形成对比。
3At one point, it seemed certain that their plane would crash.
在某个时刻，飞机似乎肯定要坠毁了。
一般过去时 (Simple Past) / 过去将来时 (would) · It seemed + 形容词 + that 从句（would + 动词原形）
- it seemed certain that… 似乎肯定……
- would crash 是过去将来时
- at one point 有一度
it seemed certain 后接 that 从句，从句用 would 表示从过去看将要发生的事。
4It could only get over the mountains if it rose to 10,000 feet.
只有升到10,000英尺的高度，飞机才能飞过这些山。
一般过去时 (Simple Past) · 主语 + could only + 动词原形 + if + 条件从句
- could 表示过去具备的能力/可能性
- only 修饰整个条件
- if 从句用一般过去时
could 在此说明只有升到一万英尺才可能飞过去，不是强调成功完成。
5Byrd at once ordered his men to throw out two heavy food sacks.
伯德立即命令手下扔掉两个沉重的食品袋。
一般过去时 (Simple Past) · 主语 + at once + ordered + 宾语 + to + 动词原形
- order sb. to do sth. 命令某人做某事
- throw out 扔掉
- at once 立刻
ordered 后接“宾语 + 不定式”，表示命令的内容。
6The plane was then able to rise and it cleared the mountains by 400 feet.
飞机于是得以上升，以400英尺的高度差飞过了山顶。
一般过去时 (Simple Past) · 主语 + was then able to + 动词原形 + and + 主语 + 动词过去式 + by + 数量
- was able to rise 表示经过努力成功升高
- clear … by 400 feet 以 400 英尺的距离越过
- then 表示随后
was able to 强调在具体场合成功做到，与前面 could 的用法形成对比。
7Byrd now knew that he would be able to reach the South Pole which was 300 miles away, for there were no more mountains in sight.
伯德此时知道他能够抵达300英里之外的南极了，因为前方再也看不到山了。
一般过去时 (Simple Past) / 过去将来时 (would be able to) · 主语 + knew + that + 主语 + would be able to + 动词原形 + 定语从句, for + 原因从句
- would be able to 是 will be able to 的过去式
- which was 300 miles away 修饰 the South Pole
- for 引导原因，in sight 在视野内
can 没有将来式，要用 be able to；宾语从句中随主句变为 would be able to。
8The aircraft was able to fly over the endless white plains without difficulty.
飞机得以毫无困难地飞越了那一望无际的白色平原。
一般过去时 (Simple Past) · 主语 + was able to + 动词原形 + 地点 + without + 名词
- was able to fly 表示顺利完成
- without difficulty 毫无困难
- endless white plains 一望无际的白色平原
was able to 描述飞机顺利完成了飞越平原的动作。

练习 · 44 题

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选择正确答案
1. The plane was then ____ rise and it cleared the mountains by 400 feet.
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2. Byrd knew that he ____ reach the South Pole, for there were no more mountains in sight.
选择正确答案
3. After they threw out the heavy sacks, the men ____ save the plane.
选择正确答案
4. At first, Byrd and his men ____ take a great many photographs of the mountains.
选择正确答案
5. It ____ only get over the mountains if it rose to 10,000 feet.
选择正确答案
6. If the weather is good tomorrow, we ____ see the mountains from the aircraft.
选择正确答案
7. Byrd ____ fly a plane when he was a young man.
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8. At one point, it seemed certain that their plane ____.
选择正确答案
9. Byrd at once ordered his men ____ two heavy food sacks.
选择正确答案
10. The aircraft was able to fly over the endless white plains ____ difficulty.