What is the difference between 能 and 能够? I understand there is a difference between 可以, 能, and 会 in Mandarin. But is there any difference between 能 and 能够?

Also, is there any case where one word can be used but the other cannot?

At least I just got to know that 能够 cannot take a one-syllable verb (while 能 can). So it is not correct to say 她能够吃, but is there any other difference?
Both 能 and 能够 mean 'can/ able to'

Subtle difference:


能 mostly refer to 有能力 (capable/ able)
够 in 能够 carries the additional meaning of '足夠' (enough to)


Example:

"Three inch of water can (is capable of) drown a person" 三英寸的水能淹死一個人 

"Three inch of water can (be enough to) drown a person" 三英寸的水能够淹死一個人 

"one dollar can (is able to) buy one Doughnut" 一美元能買一個甜甜圈

"one million dollar can (be enough to) buy a persons principle" 一百萬美元能够買一個人的原則