Note that capable and able 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, capable 和 able 都可用来表示能够做某事。able 表示具有必要知识或技能, 或者表示可能性: He wondered if he would be able to climb over the rail (他在想自己能不能翻越围栏)，They were able to use their profits for new investments (他们得以将利润用于新的投资)。注意, 如果用过去时, 则表示实际已经做了: We were able to reduce costs (我们得以降低成本)。capable表示具有所需的知识或技能, 或者表示可能做某事: The workers are perfectly capable of running the organization themselves (工人们完全有能力自己管理这个组织)，She was quite capable of falling asleep (她很容易睡着)。capable 后也可表示具有某种情感或做出某一行为: He's capable of loyalty (他能做到忠心耿耿)，Bowman could not believe him capable of murder (鲍曼不相信他会杀人)。capable of 还可以用于描述汽车或机器等的性能: The car was capable of 110 miles per hour (该车时速能达到110英里)。able 或 capable 用来形容人时表示“有能力的”、“能力强的”：He's certainly a capable gardener (他绝对是个能干的园丁)。