able -> unable 反义词 不能够（……的）
able -> ability 变成名词 能力，才能
able -> disable v. 使 … 失去能力 -> disabled adj. 残废的；有缺陷的
be able to do sth. 能够/有能力做某事 = have the ability to do sth.
He is a clever boy. He is always able to come up with good ideas.
= He is a clever boy. He has the ability to come up with good ideas.
be able to与can
Can I come in?我可以进来吗?
That can’t be true.那不可能是真的。
以上两句都不可换用be able to。
2.can只有现在时和过去时两种形式,而be able to则有多种时态形式。试比较下面两句:
Will you be able to come tomorrow?
This factory has been able to produce newly-devised sewing machines.
3.在be able to之前可加用另外一个助动词,且多用于否定或疑问结构,而can则无此用法。
4.用于否定结构, be able to表达一时情况,而can则表达往常情况。试比较下面两句:
He is not able to swim today.
He can’t swim at all.
5.be able to后可接系表结构,表示一种状态或性质;而can没有这种用法。例如:
He was able to be cold about her now.他现在对她可能有些冷淡。
6.be able to有非谓语动词形式,而can则没有。例如:
I hope to be able to do the work.我希望能做这项工作。
You must be able to speak French for this job.
A viral illness left her barely able to walk.
I didn’t feel able to disagree with him.
Will you be able to come?
⇨ note at can ¹
2. (abler / 5eiblE(r) / , ablest / 5eiblist / ) intelligent; good at sth
the ablest student in the class
We aim to help the less able in society to lead an independent life.
⇨ see also ably
able adj. ( ≠ unable )
ability n. ( ≠ inability )
1. be able to do sth
a. to have the skill, strength, knowledge etc needed to do something有能力做某事，会做某事:
2. clever or good at doing something熟练的; 精通〔某事〕的:
- The older child should be able to prepare a simple meal…那个年纪稍大的孩子应当会做一顿简单的饭菜。
- The company say they’re able to keep pricing competitive…该公司说他们能够使定价保持竞争力。
- They seemed able to work together very efficiently.他们看来能很有效率地合作。
- You’ll be able to read in peace…你就能安心地读书了。
- Have you been able to have any kind of contact?…你联系上了吗？
- It would be nice to be able to afford to retire earlier.无后顾之忧而能提早退休当是件幸事。
- …one of the brightest and ablest members of the government…政府里最聪明能干的成员之一
- They are bright, intelligent, able and confident.他们聪明又智慧，能干又自信。
Usage Note :Note that able and capable are both used to say that someone can do something. When you say that someone is able to do something, you mean that they can do it either because of their knowledge or skill, or because it is possible. He wondered if he would be able to climb over the rail… They were able to use their profits for new investments. Note that if you use a past tense, you are saying that someone has actually done something. We were able to reduce costs. When you say that someone is capable of doing something, you mean either that they have the knowledge and skill to do it, or that they are likely to do it. The workers are perfectly capable of running the organization themselves… She was quite capable of falling asleep. You can say that someone is capable of a particular feeling or action. He’s capable of loyalty… Bowman could not believe him capable of murder. You can also use ‘capable of’ when talking about what something such as a car or machine can do. The car was capable of 110 miles per hour. If you describe someone as able or capable, you mean that they do things well. He’s certainly a capable gardener.
注意，able和capable都用来表示某人能做某事。able 既可表示因拥有某种知识或技能而能做某事，也可表示客观可能：He wondered if he would be able to climb over the rail (他不知自己能否攀过栏杆)，They were able to use their profits for new investments (他们得以将利润用于再投资)。要注意的是，如果用过去时，则表示实际做了该事：We were able to reduce costs (我们做到了降低成本)。capable既可表示具有做某事的技能或知识，也可表示做某事有较大的可能性:The workers are perfectly capable of running the organization themselves (工人完全能够自己管理这个机构)，She was quite capable of falling asleep (她很容易睡着)。capable 还可表示具有某种情感或能够做出某一行为：He’s capable of loyalty (他能做到忠心耿耿)，Bowman could not believe him capable of murder (鲍曼无法相信他会杀人)。capable亦用于指汽车、机器等的性能：The car was capable of 110 miles per hour (这辆车时速可达110英里)。able或capable形容人时表示“有能力的”、“能力强的”：He’s certainly a capable gardener (他绝对是一名能干的园丁)。
1 not used before a noun
a : having the power, skill, money, etc., that is needed to do something能，能够（指具备足够的能力、技能、金钱等）
He will buy a new car as soon as he is able.等条件允许他就会买辆新车。
— usually followed by to + verb通常接动词不定式
He will buy a new car as soon as he is able to do so.等条件允许他就会买辆新车。
Is he able to swim? [=can he swim?]他会游泳吗？
They weren’t able to afford a vacation. [=they were unable to afford a vacation]他们负担不起度假的费用
I was so tired that I was barely/hardly able to get out of bed.我累坏了，几乎起不了床。
A weight lifter is able to lift [=can lift] a very heavy weight.举重运动员能举起很重的重量。
b : not prevented from doing something : having the freedom or opportunity to do something可以；有机会
Come for a visit when you are able (to).有空时请过来玩。
— usually followed by to + verb通常接动词不定式
Will you be able to visit soon?你很快就能过来玩吗？
We were able to leave at noon.我们中午就能出发。
c — used to say that the quality or condition of something makes something possible（质量或条件）使有可能
a car that is able to hold [=can hold] five people能乘坐五个人的轿车
The car wasn’t able to be repaired. [=could not be repaired]这辆汽车没法再修了。
2 [also more able; most able] abler; ablest : having skill or talent有能力的；有技能的；有天赋的
He turned out to be an able editor/leader/soldier.他成为了一位能干的编辑/领导/军人。
She is one of the ablest lawyers in the firm.她是公司里最能干的律师之一。