Giving Invitations:
What are you doing on (day/date)?
You are invited to…
Would you like to. . .?
I’d like to invite you to. . .

Accepting Invitations:
Sure. Thank you for the invitation.
When is it?
Let’s meet at. . .
What time does it start/end?
Yes, I can’t wait !
Yes, I am very excited !

Refusing invitations:
No, thank you.
I’m sorry, but I have to. . .
I am not available.
I cannot attend.
I can’t. I’m sorry.