Example 1 You : Would you like to join us in the party tonight? Friends : Sure. You : Ok. See you at Peter's house tonight at 9 pm.
Example 2 You : Are you coming to the party tonight? Friend : I'm afraid not. You : How come? Friend : I have to study for an exam tomorrow. You : Well. In that case, I will have to let you go. Friend : Sorry. Maybe next time.
Example 3 You : Do you want to join the party tonight? Friend : I wish I could but I have to visit my grandmother. You : That's alright.