The word(s) "could" appears 96 time(s) in 90 verse(s) in Quran in Mohsin Khan translation.

(21) Had it been a near gain (booty in front of them) and an easy journey, they would have followed you, but the distance (Tabuk expedition) was long for them; and they would swear by Allah, "If we only could, we would certainly have come forth with you." They destroy their ownselves, and Allah knows that they are liars.

(22) They swear by Allah that they said nothing (bad), but really they said the word of disbelief, and they disbelieved after accepting Islam, and they resolved that (plot to murder Prophet Muhammad صلى الله عليه وسلم) which they were unable to carry out, and they could not find any cause to do so except that Allah and His Messenger had enriched them of His Bounty. If then they repent, it will be better for them, but if they turn away, Allah will punish them with a painful torment in this worldly life and in the Hereafter. And there is none for them on earth as a Wali (supporter, protector) or a helper.

(23) Those who defame such of the believers who give charity (in Allah's Cause) voluntarily, and such who could not find to give charity (in Allah's Cause) except what is available to them - so they mock at them (believers); Allah will throw back their mockery on them, and they shall have a painful torment.

(24) Those who stayed away (from Tabuk expedition) rejoiced in their staying behind the Messenger of Allah; they hated to strive and fight with their properties and their lives in the Cause of Allah, and they said: "March not forth in the heat." Say: "The Fire of Hell is more intense in heat"; if only they could understand!

(25) Nor (is there blame) on those who came to you to be provided with mounts, when you said: "I can find no mounts for you," they turned back, while their eyes overflowing with tears of grief that they could not find anything to spend (for Jihad).

(26) And this Qur'an is not such as could ever be produced by other than Allah (Lord of the heavens and the earth), but it is a confirmation of (the revelation) which was before it [i.e. the Taurat (Torah), and the Injeel (Gospel)], and a full explanation of the Book (i.e. laws, decreed for mankind) - wherein there is no doubt - from the Lord of the 'Alamin (mankind, jinn, and all that exists).

(27) Nay, they have belied the knowledge whereof they could not comprehend and what has not yet been fulfilled (i.e. their punishment). Thus those before them did belie. Then see what was the end of the Zalimun (polytheists and wrong-doers)!

(28) By no means will they escape (from Allah's Torment) on earth, nor have they protectors besides Allah! Their torment will be doubled! They could not bear to hear (the preachers of the truth) and they used not to see (the truth because of their severe aversion, in spite of the fact that they had the sense of hearing and sight).

(29) He said: "Would that I had strength (men) to overpower you, or that I could betake myself to some powerful support (to resist you)."

(30) And if your Lord had so willed, He could surely have made mankind one Ummah [nation or community (following one religion i.e. Islam)] but they will not cease to disagree.