able 最常用词，多用于褒义，着重指多方面的，经常性的，或潜在性的能力。有时也指高超、非凡的能力。
capable 语气弱于able，指有能力、有潜力或有条件做某事，常与of连用。
competent 强调具有能胜任某项工作的足够技能或其它所需的条件。
参考例句
1. Able to write market inspection report. 能够撰写市场调查报告；
2. You should be able to hear us from the chapel. 你从小礼拜堂里应该能听到我们的声音。
3. Will we be able to select more than 12 units at the same time? 我们将能够在同一个时间选择超过12个的个体单位吗?
英英解释
adj.
1. (usually followed by `to') having the necessary means or skill or know-how or authority to do someth
2. have the skills and qualifications to do things well
3. having inherent physical or mental ability or capacity
4. having a strong healthy body
