One way of agreeing, and practising your grammar at the same time, is an 'echo' response. You 'repeat' what the other person has said, but using a pronoun and the auxiliary verb. Kia's very pretty, isn't she? ====== She is. These books have become popular.==========They certainly have John works hard. ======== Yes, he does. (or even 'He does, doesn't he?)

There are many ways to say yes it depends on the case or the given question...but here are some ways to say it in general: yup ..yeah right.. true.. sure... no problem.. affirmative.. definitely.. all right.. okay.. why not? agreed.. fair enough ..certainly.. positive.. by all means.. absolutely.. guaranteed.. clearly aand many more.. :) u can also use I'm in it...Let's do it.. What are we waiting for...I was born for it... ect.. :)

apart from the cool advice above, maybe'I see what you mean' , an 'mmm', head nod/cue. Like in any langauge I think it will depend on the context/situation, your personality - not least if it's in the middle of a conversation or in a student classroom context e.g... There are some ways in link below that I use, am aware about...... Depends on your personality I guess after you're at a certain level as to which words you choose to express yourself with... https://www.englishclub.com/speaking/agreeing-disagreeing-expressions.htm