Promise is both a verb and a noun, so you can use it in two ways. "I promise that I will come back." -- This means that I am saying that I give you my word (promise) that I will come back. (VERB) OR "My promise to you is that I will come back." -- This means the same thing, but I use promise as the subject. (NOUN) Using promising is a little different. It can be a form of the verb promise, or it can be used as an adjective. "The most promising companies in the world had gathered for the conference." -- Here it means that the companies that showed promise/future success were all together at the conference. (ADJ) You could also use it this way: "The fact that she was promising good results was hopeful." -- This means that since she was giving her word/promise now, it was more comforting. (-ing VERB) I hope it helped. If you have any questions, just ask :)

1- promise (verb) & (noun) 'I promise I'll do my best to help you.' 'It would be wrong to break your promise.' 'He lent me the books as promised.' 2- promise (noun): a sign that somebody/something will be successful 'Sally shows great promise as a scholar. She’s really going to have a good future.' promising (adjective): showing signs of being good or successful 'Sally is quite young, but she's very promising.'