Two conversations run as follows:
(1)--How about going to the new movie tonight?
--__________. It's said to be one of the ten best movies so far this year.
Could I use "That's OK." to reply to this question?
(2) --Can you keep an eye on my bag, please? I want to use the bathroom.
---______________. It'll be safe with me.
Could I use "All right." to reply to this question?
Thanks for your help!
If it is an invitation, then your responses to #1 could be "OK", "Fine", "That sounds lovely", "That's a good idea", "What a great idea", "All right" and various other things, but not "That's OK".
Remember - if you don't use correct capitalisation, punctuation and spacing, anything you write will be incorrect.
So "OK" means "All right" as a response to an invitation.
"That's OK" means "Something is right or fine"
"OK " doesn't equal "that's OK."
Am I right?
PS: As for the second question, could I use "Go ahead" as a possible response?
Yes to everything you just said.
I'm not a teacher, but I write for a living. Please don't ask me about 2nd conditionals, but I'm a safe bet for what reads well in (American) English.